Ejemplo n.º 1
0
    def _initialize_index(self, data_file, regions):
        pcount = sum(data_file.total_particles.values())
        morton = np.empty(pcount, dtype='uint64')
        if pcount == 0: return morton
        mylog.debug("Initializing index % 5i (% 7i particles)",
                    data_file.file_id, pcount)
        ind = 0
        with h5py.File(data_file.filename, mode="r") as f:
            if not f.keys(): return None
            dx = np.finfo(f["FOF"]['CenterOfMass'].dtype).eps
            dx = 2.0 * self.ds.quan(dx, "code_length")

            for ptype in data_file.ds.particle_types_raw:
                if data_file.total_particles[ptype] == 0: continue
                pos = f[ptype]["CenterOfMass"][()].astype("float64")
                pos = np.resize(pos, (data_file.total_particles[ptype], 3))
                pos = data_file.ds.arr(pos, "code_length")

                # These are 32 bit numbers, so we give a little lee-way.
                # Otherwise, for big sets of particles, we often will bump into the
                # domain edges.  This helps alleviate that.
                np.clip(pos, self.ds.domain_left_edge + dx,
                        self.ds.domain_right_edge - dx, pos)
                if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
                   np.any(pos.max(axis=0) > self.ds.domain_right_edge):
                    raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0),
                                           self.ds.domain_left_edge,
                                           self.ds.domain_right_edge)
                regions.add_data_file(pos, data_file.file_id)
                morton[ind:ind + pos.shape[0]] = compute_morton(
                    pos[:, 0], pos[:, 1], pos[:, 2],
                    data_file.ds.domain_left_edge,
                    data_file.ds.domain_right_edge)
                ind += pos.shape[0]
        return morton
Ejemplo n.º 2
0
Archivo: io.py Proyecto: sheagk/yt
    def _initialize_index(self, data_file, regions):
        if self.index_ptype == "all":
            ptypes = self.ds.particle_types_raw
            pcount = sum(data_file.total_particles.values())
        else:
            ptypes = [self.index_ptype]
            pcount = data_file.total_particles[self.index_ptype]
        morton = np.empty(pcount, dtype='uint64')
        if pcount == 0: return morton
        mylog.debug("Initializing index % 5i (% 7i particles)",
                    data_file.file_id, pcount)
        ind = 0
        with h5py.File(data_file.filename, "r") as f:
            if not f.keys(): return None
            dx = np.finfo(f["Group"]["GroupPos"].dtype).eps
            dx = 2.0 * self.ds.quan(dx, "code_length")

            for ptype in ptypes:
                if data_file.total_particles[ptype] == 0:
                    continue
                pos = data_file._get_particle_positions(ptype, f=f)
                pos = self.ds.arr(pos, "code_length")

                if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
                   np.any(pos.max(axis=0) > self.ds.domain_right_edge):
                    raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0),
                                           self.ds.domain_left_edge,
                                           self.ds.domain_right_edge)
                regions.add_data_file(pos, data_file.file_id)
                morton[ind:ind + pos.shape[0]] = compute_morton(
                    pos[:, 0], pos[:, 1], pos[:, 2], self.ds.domain_left_edge,
                    self.ds.domain_right_edge)
                ind += pos.shape[0]
        return morton
Ejemplo n.º 3
0
 def _initialize_index(self, data_file, regions):
     pcount = data_file.header["num_halos"]
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug("Initializing index % 5i (% 7i particles)",
                 data_file.file_id, pcount)
     ind = 0
     with h5py.File(data_file.filename, "r") as f:
         if not f.keys(): return None
         pos = np.empty((pcount, 3), dtype="float64")
         pos = data_file.ds.arr(pos, "code_length")
         dx = np.finfo(f['particle_position_x'].dtype).eps
         dx = 2.0*self.ds.quan(dx, "code_length")
         pos[:,0] = f["particle_position_x"].value
         pos[:,1] = f["particle_position_y"].value
         pos[:,2] = f["particle_position_z"].value
         # These are 32 bit numbers, so we give a little lee-way.
         # Otherwise, for big sets of particles, we often will bump into the
         # domain edges.  This helps alleviate that.
         np.clip(pos, self.ds.domain_left_edge + dx,
                      self.ds.domain_right_edge - dx, pos)
         if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
            np.any(pos.max(axis=0) > self.ds.domain_right_edge):
             raise YTDomainOverflow(pos.min(axis=0),
                                    pos.max(axis=0),
                                    self.ds.domain_left_edge,
                                    self.ds.domain_right_edge)
         regions.add_data_file(pos, data_file.file_id)
         morton[ind:ind+pos.shape[0]] = compute_morton(
             pos[:,0], pos[:,1], pos[:,2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge)
     return morton
Ejemplo n.º 4
0
 def _initialize_index(self, data_file, regions):
     index_ptype = self.index_ptype
     f = h5py.File(data_file.filename, "r")
     if index_ptype == "all":
         pcount = f["/Header"].attrs["NumPart_ThisFile"][:].sum()
         keys = f.keys()
     else:
         pt = int(index_ptype[-1])
         pcount = f["/Header"].attrs["NumPart_ThisFile"][pt]
         keys = [index_ptype]
     morton = np.empty(pcount, dtype='uint64')
     ind = 0
     for key in keys:
         if not key.startswith("PartType"): continue
         if "Coordinates" not in f[key]: continue
         ds = f[key]["Coordinates"]
         dt = ds.dtype.newbyteorder("N") # Native
         pos = np.empty(ds.shape, dtype=dt)
         pos[:] = ds
         regions.add_data_file(pos, data_file.file_id,
                               data_file.ds.filter_bbox)
         morton[ind:ind+pos.shape[0]] = compute_morton(
             pos[:,0], pos[:,1], pos[:,2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge,
             data_file.ds.filter_bbox)
         ind += pos.shape[0]
     f.close()
     return morton
Ejemplo n.º 5
0
Archivo: io.py Proyecto: tukss/yt
 def _initialize_index(self, data_file, regions):
     pcount = data_file.header["num_halos"]
     morton = np.empty(pcount, dtype="uint64")
     mylog.debug("Initializing index % 5i (% 7i particles)",
                 data_file.file_id, pcount)
     if pcount == 0:
         return morton
     ind = 0
     ptype = "halos"
     with open(data_file.filename, "rb") as f:
         pos = data_file._get_particle_positions(ptype, f=f)
         pos = data_file.ds.arr(pos, "code_length")
         if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or np.any(
                 pos.max(axis=0) > self.ds.domain_right_edge):
             raise YTDomainOverflow(
                 pos.min(axis=0),
                 pos.max(axis=0),
                 self.ds.domain_left_edge,
                 self.ds.domain_right_edge,
             )
         regions.add_data_file(pos, data_file.file_id)
         morton[ind:ind + pos.shape[0]] = compute_morton(
             pos[:, 0],
             pos[:, 1],
             pos[:, 2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge,
         )
     return morton
Ejemplo n.º 6
0
    def _initialize_index(self, data_file, regions):
        dle = self.ds.domain_left_edge.in_units("code_length").d
        dre = self.ds.domain_right_edge.in_units("code_length").d
        pcount = 0
        for dd in self.ds.midx.iter_bbox_data(
            dle, dre,
            ['x']):
            pcount += dd['x'].size

        morton = np.empty(pcount, dtype='uint64')
        ind = 0

        chunk_id = 0
        for dd in self.ds.midx.iter_bbox_data(
            dle, dre,
            ['x','y','z']):
            npart = dd['x'].size
            pos = np.empty((npart, 3), dtype=dd['x'].dtype)
            pos[:,0] = dd['x']
            pos[:,1] = dd['y']
            pos[:,2] = dd['z']
            if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
               np.any(pos.max(axis=0) > self.ds.domain_right_edge):
                raise YTDomainOverflow(pos.min(axis=0),
                                       pos.max(axis=0),
                                       self.ds.domain_left_edge,
                                       self.ds.domain_right_edge)
            regions.add_data_file(pos, chunk_id)
            morton[ind:ind+npart] = compute_morton(
                pos[:,0], pos[:,1], pos[:,2],
                data_file.ds.domain_left_edge,
                data_file.ds.domain_right_edge)
            ind += npart
        return morton
Ejemplo n.º 7
0
 def _initialize_index(self, data_file, regions):
     pcount = data_file.header["num_halos"]
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug("Initializing index % 5i (% 7i particles)",
                 data_file.file_id, pcount)
     ind = 0
     with open(data_file.filename, "rb") as f:
         f.seek(data_file._position_offset, os.SEEK_SET)
         halos = np.fromfile(f, dtype=self._halo_dt, count = pcount)
         pos = np.empty((halos.size, 3), dtype="float64")
         # These positions are in Mpc, *not* "code" units
         pos = data_file.ds.arr(pos, "code_length")
         dx = np.finfo(halos['particle_position_x'].dtype).eps
         dx = 2.0*self.ds.quan(dx, "code_length")
         pos[:,0] = halos["particle_position_x"]
         pos[:,1] = halos["particle_position_y"]
         pos[:,2] = halos["particle_position_z"]
         # These are 32 bit numbers, so we give a little lee-way.
         # Otherwise, for big sets of particles, we often will bump into the
         # domain edges.  This helps alleviate that.
         np.clip(pos, self.ds.domain_left_edge + dx,
                      self.ds.domain_right_edge - dx, pos)
         #del halos
         if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
            np.any(pos.max(axis=0) > self.ds.domain_right_edge):
             raise YTDomainOverflow(pos.min(axis=0),
                                    pos.max(axis=0),
                                    self.ds.domain_left_edge,
                                    self.ds.domain_right_edge)
         regions.add_data_file(pos, data_file.file_id)
         morton[ind:ind+pos.shape[0]] = compute_morton(
             pos[:,0], pos[:,1], pos[:,2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge)
     return morton
Ejemplo n.º 8
0
Archivo: io.py Proyecto: pshriwise/yt
    def _initialize_index(self, data_file, regions):
        pcount = data_file.ds.parameters["nhalos"] + data_file.ds.parameters[
            "nsubs"]
        morton = np.empty(pcount, dtype="uint64")
        mylog.debug("Initializing index % 5i (% 7i particles)",
                    data_file.file_id, pcount)
        if pcount == 0:
            return morton
        ind = 0

        pos = self._get_particle_positions()

        if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or np.any(
                pos.max(axis=0) > self.ds.domain_right_edge):
            raise YTDomainOverflow(
                pos.min(axis=0),
                pos.max(axis=0),
                self.ds.domain_left_edge,
                self.ds.domain_right_edge,
            )
        regions.add_data_file(pos, data_file.file_id)
        morton[ind:ind + pos.shape[0]] = compute_morton(
            pos[:, 0],
            pos[:, 1],
            pos[:, 2],
            data_file.ds.domain_left_edge,
            data_file.ds.domain_right_edge,
        )

        return morton
Ejemplo n.º 9
0
 def _initialize_index(self, data_file, regions):
     halos = data_file.read_data(usecols=['ID', 'Xc', 'Yc', 'Zc'])
     pcount = len(halos['ID'])
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug('Initializing index % 5i (% 7i particles)',
                 data_file.file_id, pcount)
     if pcount == 0:
         return morton
     ind = 0
     pos = np.empty((pcount, 3), dtype='float64')
     pos = data_file.ds.arr(pos, 'code_length')
     dx = np.finfo(halos['Xc'].dtype).eps
     dx = 2.0 * self.ds.quan(dx, 'code_length')
     pos[:, 0] = halos['Xc']
     pos[:, 1] = halos['Yc']
     pos[:, 2] = halos['Zc']
     dle = self.ds.domain_left_edge
     dre = self.ds.domain_right_edge
     # These are 32 bit numbers, so we give a little lee-way.
     # Otherwise, for big sets of particles, we often will bump into the
     # domain edges.  This helps alleviate that.
     np.clip(pos, dle + dx, dre - dx, pos)
     if np.any(pos.min(axis=0) < dle) or np.any(pos.max(axis=0) > dre):
         raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0), dle, dre)
     regions.add_data_file(pos, data_file.file_id)
     morton[ind:ind + pos.shape[0]] = compute_morton(
         pos[:, 0], pos[:, 1], pos[:, 2], dle, dre)
     return morton
Ejemplo n.º 10
0
    def _initialize_index(self, data_file, regions):
        dle = self.ds.domain_left_edge.in_units("code_length").d
        dre = self.ds.domain_right_edge.in_units("code_length").d
        pcount = 0
        for dd in self.ds.midx.iter_bbox_data(dle, dre, ["x"]):
            pcount += dd["x"].size

        morton = np.empty(pcount, dtype="uint64")
        ind = 0

        chunk_id = 0
        for dd in self.ds.midx.iter_bbox_data(dle, dre, ["x", "y", "z"]):
            npart = dd["x"].size
            pos = np.empty((npart, 3), dtype=dd["x"].dtype)
            pos[:, 0] = dd["x"]
            pos[:, 1] = dd["y"]
            pos[:, 2] = dd["z"]
            if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or np.any(
                    pos.max(axis=0) > self.ds.domain_right_edge):
                raise YTDomainOverflow(
                    pos.min(axis=0),
                    pos.max(axis=0),
                    self.ds.domain_left_edge,
                    self.ds.domain_right_edge,
                )
            regions.add_data_file(pos, chunk_id)
            morton[ind:ind + npart] = compute_morton(
                pos[:, 0],
                pos[:, 1],
                pos[:, 2],
                data_file.ds.domain_left_edge,
                data_file.ds.domain_right_edge,
            )
            ind += npart
        return morton
Ejemplo n.º 11
0
 def _initialize_index(self, data_file, regions):
     pcount = data_file.header["num_halos"]
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug("Initializing index % 5i (% 7i particles)",
                 data_file.file_id, pcount)
     ind = 0
     with h5py.File(data_file.filename, "r") as f:
         if not f.keys(): return None
         pos = np.empty((pcount, 3), dtype="float64")
         pos = data_file.ds.arr(pos, "code_length")
         dx = np.finfo(f['particle_position_x'].dtype).eps
         dx = 2.0*self.ds.quan(dx, "code_length")
         pos[:,0] = f["particle_position_x"].value
         pos[:,1] = f["particle_position_y"].value
         pos[:,2] = f["particle_position_z"].value
         # These are 32 bit numbers, so we give a little lee-way.
         # Otherwise, for big sets of particles, we often will bump into the
         # domain edges.  This helps alleviate that.
         np.clip(pos, self.ds.domain_left_edge + dx,
                      self.ds.domain_right_edge - dx, pos)
         if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
            np.any(pos.max(axis=0) > self.ds.domain_right_edge):
             raise YTDomainOverflow(pos.min(axis=0),
                                    pos.max(axis=0),
                                    self.ds.domain_left_edge,
                                    self.ds.domain_right_edge)
         regions.add_data_file(pos, data_file.file_id)
         morton[ind:ind+pos.shape[0]] = compute_morton(
             pos[:,0], pos[:,1], pos[:,2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge)
     return morton
Ejemplo n.º 12
0
 def morton(self):
     self.validate()
     eps = np.finfo(self.dtype).eps
     LE = self.min(axis=0)
     LE -= np.abs(LE) * eps
     RE = self.max(axis=0)
     RE += np.abs(RE) * eps
     morton = compute_morton(self[:, 0], self[:, 1], self[:, 2], LE, RE)
     return morton
 def morton(self):
     self.validate()
     eps = np.finfo(self.dtype).eps
     LE = self.min(axis=0)
     LE -= np.abs(LE) * eps
     RE = self.max(axis=0)
     RE += np.abs(RE) * eps
     morton = compute_morton(
         self[:,0], self[:,1], self[:,2],
         LE, RE)
     return morton
Ejemplo n.º 14
0
 def _initialize_index(self, data_file, regions):
     count = sum(data_file.total_particles.values())
     DLE = data_file.ds.domain_left_edge
     DRE = data_file.ds.domain_right_edge
     with open(data_file.filename, "rb") as f:
         # We add on an additionally 4 for the first record.
         f.seek(data_file._position_offset + 4)
         # The first total_particles * 3 values are positions
         pp = np.fromfile(f, dtype = 'float32', count = count*3)
         pp.shape = (count, 3)
     regions.add_data_file(pp, data_file.file_id, data_file.ds.filter_bbox)
     morton = compute_morton(pp[:,0], pp[:,1], pp[:,2], DLE, DRE,
                             data_file.ds.filter_bbox)
     return morton
Ejemplo n.º 15
0
 def _get_morton_from_position(self, data_file, count, offset_count,
                               regions, DLE, DRE):
     with open(data_file.filename, "rb") as f:
         # We add on an additionally 4 for the first record.
         f.seek(data_file._position_offset + 4 + offset_count * 12)
         # The first total_particles * 3 values are positions
         pp = np.fromfile(f, dtype=self._endian + self._float_type,
                          count=count * 3)
         pp.shape = (count, 3)
         pp = pp.astype(self._float_type)
     regions.add_data_file(pp, data_file.file_id,
                               data_file.ds.filter_bbox)
     morton = compute_morton(pp[:, 0], pp[:, 1], pp[:, 2], DLE, DRE,
                             data_file.ds.filter_bbox)
     return morton
Ejemplo n.º 16
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 def _initialize_index(self, data_file, regions):
     totcount = 4096**2 #file is always this size
     count = data_file.ds.parameters['lspecies'][-1]
     DLE = data_file.ds.domain_left_edge
     DRE = data_file.ds.domain_right_edge
     dx = (DRE - DLE) / 2**_ORDER_MAX
     with open(data_file.filename, "rb") as f:
         # The first total_particles * 3 values are positions
         pp = np.fromfile(f, dtype = '>f4', count = totcount*3)
         pp.shape = (3, totcount)
         pp = pp[:,:count] #remove zeros
         pp = np.transpose(pp).astype(np.float32) #cast as float32 for compute_morton
         pp = (pp - 1.)/data_file.ds.parameters['ng'] #correct the dm particle units
     regions.add_data_file(pp, data_file.file_id)
     morton = compute_morton(pp[:,0], pp[:,1], pp[:,2], DLE, DRE)
     return morton
Ejemplo n.º 17
0
 def _initialize_index(self, data_file, regions):
     totcount = 4096**2  #file is always this size
     count = data_file.ds.parameters['lspecies'][-1]
     DLE = data_file.ds.domain_left_edge
     DRE = data_file.ds.domain_right_edge
     with open(data_file.filename, "rb") as f:
         # The first total_particles * 3 values are positions
         pp = np.fromfile(f, dtype='>f4', count=totcount * 3)
         pp.shape = (3, totcount)
         pp = pp[:, :count]  #remove zeros
         pp = np.transpose(pp).astype(
             np.float32)  #cast as float32 for compute_morton
         pp = (pp - 1.) / data_file.ds.parameters[
             'ng']  #correct the dm particle units
     regions.add_data_file(pp, data_file.file_id)
     morton = compute_morton(pp[:, 0], pp[:, 1], pp[:, 2], DLE, DRE)
     return morton
Ejemplo n.º 18
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 def _initialize_index(self, data_file, regions):
     header = self.ds.parameters
     ptypes = header["particle_count"][data_file.file_id].keys()
     pcount = sum(header["particle_count"][data_file.file_id].values())
     morton = np.empty(pcount, dtype='uint64')
     ind = 0
     for ptype in ptypes:
         s = self._open_stream(data_file, (ptype, "Coordinates"))
         c = np.frombuffer(s, dtype="float64")
         c.shape = (c.shape[0] / 3.0, 3)
         regions.add_data_file(c, data_file.file_id,
                               data_file.ds.filter_bbox)
         morton[ind:ind + c.shape[0]] = compute_morton(
             c[:, 0], c[:, 1], c[:, 2], data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge, data_file.ds.filter_bbox)
         ind += c.shape[0]
     return morton
Ejemplo n.º 19
0
    def _initialize_index(self, data_file, regions):
        x, y, z = (self._handle[ax] for ax in 'xyz')
        pcount = x.size

        morton = np.empty(pcount, dtype='uint64')
        ind = 0
        while ind < pcount:
            npart = min(CHUNKSIZE, pcount - ind)
            pos = np.empty((npart, 3), dtype=x.dtype)
            pos[:, 0] = x[ind:ind + npart]
            pos[:, 1] = y[ind:ind + npart]
            pos[:, 2] = z[ind:ind + npart]
            regions.add_data_file(pos, data_file.file_id)
            morton[ind:ind + npart] = compute_morton(
                pos[:, 0], pos[:, 1], pos[:, 2], data_file.ds.domain_left_edge,
                data_file.ds.domain_right_edge)
            ind += CHUNKSIZE
        return morton
Ejemplo n.º 20
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 def _morton_index(field, data):
     """This is the morton index, which is properly a uint64 field.  Because
     we make some assumptions that the fields returned by derived fields are
     float64, this returns a "view" on the data that is float64.  To get
     back the original uint64, you need to call .view("uint64") on it;
     however, it should be true that if you sort the uint64, you will get
     the same order as if you sort the float64 view.
     """
     eps = np.finfo("f8").eps
     uq = data.ds.domain_left_edge.uq
     LE = data.ds.domain_left_edge - eps * uq
     RE = data.ds.domain_right_edge + eps * uq
     # .ravel() only copies if it needs to
     morton = compute_morton(data["index", "x"].ravel(), data["index",
                                                              "y"].ravel(),
                             data["index", "z"].ravel(), LE, RE)
     morton.shape = data["index", "x"].shape
     return morton.view("f8")
Ejemplo n.º 21
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 def _initialize_index(self, data_file, regions):
     halos = data_file.read_data(usecols=['ID'])
     pcount = len(halos['ID'])
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug('Initializing index % 5i (% 7i particles)',
                 data_file.file_id, pcount)
     if pcount == 0:
         return morton
     ind = 0
     pos = data_file._get_particle_positions('halos')
     pos = data_file.ds.arr(pos, 'code_length')
     dle = self.ds.domain_left_edge
     dre = self.ds.domain_right_edge
     if np.any(pos.min(axis=0) < dle) or np.any(pos.max(axis=0) > dre):
         raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0), dle, dre)
     regions.add_data_file(pos, data_file.file_id)
     morton[ind:ind + pos.shape[0]] = compute_morton(
         pos[:, 0], pos[:, 1], pos[:, 2], dle, dre)
     return morton
Ejemplo n.º 22
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    def _initialize_index(self, data_file, regions):
        x, y, z = (self._handle[ax] for ax in 'xyz')
        pcount = x.size

        morton = np.empty(pcount, dtype='uint64')
        ind = 0
        while ind < pcount:
            npart = min(CHUNKSIZE, pcount - ind)
            pos = np.empty((npart, 3), dtype=x.dtype)
            pos[:,0] = x[ind:ind+npart]
            pos[:,1] = y[ind:ind+npart]
            pos[:,2] = z[ind:ind+npart]
            regions.add_data_file(pos, data_file.file_id)
            morton[ind:ind+npart] = compute_morton(
                pos[:,0], pos[:,1], pos[:,2],
                data_file.ds.domain_left_edge,
                data_file.ds.domain_right_edge)
            ind += CHUNKSIZE
        return morton
Ejemplo n.º 23
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 def _initialize_index(self, data_file, regions):
     header = self.ds.parameters
     ptypes = header["particle_count"][data_file.file_id].keys()
     pcount = sum(header["particle_count"][data_file.file_id].values())
     morton = np.empty(pcount, dtype='uint64')
     ind = 0
     for ptype in ptypes:
         s = self._open_stream(data_file, (ptype, "Coordinates"))
         c = np.frombuffer(s, dtype="float64")
         c.shape = (c.shape[0]/3.0, 3)
         regions.add_data_file(c, data_file.file_id,
                               data_file.ds.filter_bbox)
         morton[ind:ind+c.shape[0]] = compute_morton(
             c[:,0], c[:,1], c[:,2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge,
             data_file.ds.filter_bbox)
         ind += c.shape[0]
     return morton
Ejemplo n.º 24
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 def _initialize_index(self, data_file, regions):
     p_fields = self._handle["/tracer particles"]
     px, py, pz = self._position_fields
     pcount = self._count_particles(data_file)["io"]
     morton = np.empty(pcount, dtype='uint64')
     ind = 0
     while ind < pcount:
         npart = min(self._chunksize, pcount - ind)
         pos = np.empty((npart, 3), dtype="=f8")
         pos[:, 0] = p_fields[ind:ind + npart, px]
         pos[:, 1] = p_fields[ind:ind + npart, py]
         pos[:, 2] = p_fields[ind:ind + npart, pz]
         regions.add_data_file(pos, data_file.file_id)
         morton[ind:ind+npart] = \
             compute_morton(pos[:,0], pos[:,1], pos[:,2],
                            data_file.ds.domain_left_edge,
                            data_file.ds.domain_right_edge)
         ind += self._chunksize
     return morton
Ejemplo n.º 25
0
Archivo: io.py Proyecto: pshriwise/yt
    def _initialize_index(self, data_file, regions):
        all_count = self._count_particles(data_file)
        pcount = sum(all_count.values())
        morton = np.empty(pcount, dtype="uint64")
        mylog.debug("Initializing index % 5i (% 7i particles)",
                    data_file.file_id, pcount)
        ind = 0
        with h5py.File(data_file.filename, mode="r") as f:
            for ptype in all_count:
                if ptype not in f or all_count[ptype] == 0:
                    continue
                pos = np.empty((all_count[ptype], 3), dtype="float64")
                units = _get_position_array_units(ptype, f, "x")
                if ptype == "grid":
                    dx = f["grid"]["dx"][()].min()
                    dx = self.ds.quan(dx,
                                      parse_h5_attr(f["grid"]["dx"],
                                                    "units")).to("code_length")
                else:
                    dx = 2.0 * np.finfo(
                        f[ptype]["particle_position_x"].dtype).eps
                    dx = self.ds.quan(dx, units).to("code_length")
                pos[:, 0] = _get_position_array(ptype, f, "x")
                pos[:, 1] = _get_position_array(ptype, f, "y")
                pos[:, 2] = _get_position_array(ptype, f, "z")
                pos = self.ds.arr(pos, units).to("code_length")
                dle = self.ds.domain_left_edge.to("code_length")
                dre = self.ds.domain_right_edge.to("code_length")

                # These are 32 bit numbers, so we give a little lee-way.
                # Otherwise, for big sets of particles, we often will bump into the
                # domain edges.  This helps alleviate that.
                np.clip(pos, dle + dx, dre - dx, pos)
                if np.any(pos.min(axis=0) < dle) or np.any(
                        pos.max(axis=0) > dre):
                    raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0),
                                           dle, dre)
                regions.add_data_file(pos, data_file.file_id)
                morton[ind:ind + pos.shape[0]] = compute_morton(
                    pos[:, 0], pos[:, 1], pos[:, 2], dle, dre)
                ind += pos.shape[0]
        return morton
Ejemplo n.º 26
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 def _initialize_index(self, data_file, regions):
     # self.fields[g.id][fname] is the pattern here
     morton = []
     for ptype in self.ds.particle_types_raw:
         try:
             pos = np.column_stack(self.fields[data_file.filename][
                 (ptype, "particle_position_%s" % ax)] for ax in 'xyz')
         except KeyError:
             pos = self.fields[data_file.filename][ptype, "particle_position"]
         if np.any(pos.min(axis=0) < data_file.ds.domain_left_edge) or \
            np.any(pos.max(axis=0) > data_file.ds.domain_right_edge):
             raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0),
                                    data_file.ds.domain_left_edge,
                                    data_file.ds.domain_right_edge)
         regions.add_data_file(pos, data_file.file_id)
         morton.append(compute_morton(
                 pos[:,0], pos[:,1], pos[:,2],
                 data_file.ds.domain_left_edge,
                 data_file.ds.domain_right_edge))
     return np.concatenate(morton)
Ejemplo n.º 27
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 def _initialize_index(self, data_file, regions):
     # self.fields[g.id][fname] is the pattern here
     morton = []
     for ptype in self.ds.particle_types_raw:
         try:
             pos = np.column_stack(self.fields[data_file.filename][
                 (ptype, "particle_position_%s" % ax)] for ax in 'xyz')
         except KeyError:
             pos = self.fields[data_file.filename][ptype, "particle_position"]
         if np.any(pos.min(axis=0) < data_file.ds.domain_left_edge) or \
            np.any(pos.max(axis=0) > data_file.ds.domain_right_edge):
             raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0),
                                    data_file.ds.domain_left_edge,
                                    data_file.ds.domain_right_edge)
         regions.add_data_file(pos, data_file.file_id)
         morton.append(compute_morton(
                 pos[:,0], pos[:,1], pos[:,2],
                 data_file.ds.domain_left_edge,
                 data_file.ds.domain_right_edge))
     return np.concatenate(morton)
Ejemplo n.º 28
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 def _initialize_index(self, data_file, regions):
     ds = data_file.ds
     morton = np.empty(sum(data_file.total_particles.values()),
                       dtype="uint64")
     ind = 0
     DLE, DRE = ds.domain_left_edge, ds.domain_right_edge
     dx = (DRE - DLE) / (2**_ORDER_MAX)
     self.domain_left_edge = DLE.in_units("code_length").ndarray_view()
     self.domain_right_edge = DRE.in_units("code_length").ndarray_view()
     with open(data_file.filename, "rb") as f:
         f.seek(ds._header_offset)
         for iptype, ptype in enumerate(self._ptypes):
             # We'll just add the individual types separately
             count = data_file.total_particles[ptype]
             if count == 0: continue
             start, stop = ind, ind + count
             while ind < stop:
                 c = min(CHUNKSIZE, stop - ind)
                 pp = np.fromfile(f, dtype = self._pdtypes[ptype],
                                  count = c)
                 mis = np.empty(3, dtype="float64")
                 mas = np.empty(3, dtype="float64")
                 for axi, ax in enumerate('xyz'):
                     mi = pp["Coordinates"][ax].min()
                     ma = pp["Coordinates"][ax].max()
                     mylog.debug("Spanning: %0.3e .. %0.3e in %s", mi, ma, ax)
                     mis[axi] = mi
                     mas[axi] = ma
                 pos = np.empty((pp.size, 3), dtype="float64")
                 for i, ax in enumerate("xyz"):
                     eps = np.finfo(pp["Coordinates"][ax].dtype).eps
                     pos[:,i] = pp["Coordinates"][ax]
                 regions.add_data_file(pos, data_file.file_id,
                                       data_file.ds.filter_bbox)
                 morton[ind:ind+c] = compute_morton(
                     pos[:,0], pos[:,1], pos[:,2],
                     DLE, DRE, data_file.ds.filter_bbox)
                 ind += c
     mylog.info("Adding %0.3e particles", morton.size)
     return morton
Ejemplo n.º 29
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 def _initialize_index(self, data_file, regions):
     ds = data_file.ds
     morton = np.empty(sum(data_file.total_particles.values()),
                       dtype="uint64")
     ind = 0
     DLE, DRE = ds.domain_left_edge, ds.domain_right_edge
     dx = (DRE - DLE) / (2**_ORDER_MAX)
     self.domain_left_edge = DLE.in_units("code_length").ndarray_view()
     self.domain_right_edge = DRE.in_units("code_length").ndarray_view()
     with open(data_file.filename, "rb") as f:
         f.seek(ds._header_offset)
         for iptype, ptype in enumerate(self._ptypes):
             # We'll just add the individual types separately
             count = data_file.total_particles[ptype]
             if count == 0: continue
             start, stop = ind, ind + count
             while ind < stop:
                 c = min(CHUNKSIZE, stop - ind)
                 pp = np.fromfile(f, dtype=self._pdtypes[ptype], count=c)
                 mis = np.empty(3, dtype="float64")
                 mas = np.empty(3, dtype="float64")
                 for axi, ax in enumerate('xyz'):
                     mi = pp["Coordinates"][ax].min()
                     ma = pp["Coordinates"][ax].max()
                     mylog.debug("Spanning: %0.3e .. %0.3e in %s", mi, ma,
                                 ax)
                     mis[axi] = mi
                     mas[axi] = ma
                 pos = np.empty((pp.size, 3), dtype="float64")
                 for i, ax in enumerate("xyz"):
                     eps = np.finfo(pp["Coordinates"][ax].dtype).eps
                     pos[:, i] = pp["Coordinates"][ax]
                 regions.add_data_file(pos, data_file.file_id,
                                       data_file.ds.filter_bbox)
                 morton[ind:ind + c] = compute_morton(
                     pos[:, 0], pos[:, 1], pos[:, 2], DLE, DRE,
                     data_file.ds.filter_bbox)
                 ind += c
     mylog.info("Adding %0.3e particles", morton.size)
     return morton
Ejemplo n.º 30
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 def _initialize_index(self, data_file, regions):
     f = _get_h5_handle(data_file.filename)
     pcount = f["/Header"].attrs["NumPart_ThisFile"][:].sum()
     morton = np.empty(pcount, dtype='uint64')
     ind = 0
     for key in f.keys():
         if not key.startswith("PartType"): continue
         if "Coordinates" not in f[key]: continue
         ds = f[key]["Coordinates"]
         dt = ds.dtype.newbyteorder("N") # Native
         pos = np.empty(ds.shape, dtype=dt)
         pos[:] = ds
         regions.add_data_file(pos, data_file.file_id,
                               data_file.ds.filter_bbox)
         morton[ind:ind+pos.shape[0]] = compute_morton(
             pos[:,0], pos[:,1], pos[:,2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge,
             data_file.ds.filter_bbox)
         ind += pos.shape[0]
     f.close()
     return morton
Ejemplo n.º 31
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 def _initialize_index(self, data_file, regions):
     all_count = self._count_particles(data_file)
     pcount = sum(all_count.values())
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug("Initializing index % 5i (% 7i particles)",
                 data_file.file_id, pcount)
     ind = 0
     with h5py.File(data_file.filename, "r") as f:
         for ptype in all_count:
             if ptype not in f or all_count[ptype] == 0: continue
             pos = np.empty((all_count[ptype], 3), dtype="float64")
             pos = data_file.ds.arr(pos, "code_length")
             if ptype == "grid":
                 dx = f["grid"]["pdx"].value.min()
             else:
                 raise NotImplementedError
             dx = self.ds.quan(dx, "code_length")
             pos[:, 0] = _get_position_array(ptype, f, "px")
             pos[:, 1] = _get_position_array(ptype, f, "py")
             pos[:,2] = np.zeros(all_count[ptype], dtype="float64") + \
               self.ds.domain_left_edge[2].in_cgs().d
             # These are 32 bit numbers, so we give a little lee-way.
             # Otherwise, for big sets of particles, we often will bump into the
             # domain edges.  This helps alleviate that.
             np.clip(pos, self.ds.domain_left_edge + dx,
                     self.ds.domain_right_edge - dx, pos)
             if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
                np.any(pos.max(axis=0) > self.ds.domain_right_edge):
                 raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0),
                                        self.ds.domain_left_edge,
                                        self.ds.domain_right_edge)
             regions.add_data_file(pos, data_file.file_id)
             morton[ind:ind + pos.shape[0]] = compute_morton(
                 pos[:, 0], pos[:, 1], pos[:, 2],
                 data_file.ds.domain_left_edge,
                 data_file.ds.domain_right_edge)
             ind += pos.shape[0]
     return morton
Ejemplo n.º 32
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 def _initialize_index(self, data_file, regions):
     pcount = data_file.header["num_halos"]
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug("Initializing index % 5i (% 7i particles)",
                 data_file.file_id, pcount)
     ind = 0
     if pcount == 0: return None
     ptype = 'halos'
     with h5py.File(data_file.filename, "r") as f:
         if not f.keys(): return None
         units = parse_h5_attr(f["particle_position_x"], "units")
         pos = data_file._get_particle_positions(ptype, f=f)
         pos = data_file.ds.arr(pos, units).to("code_length")
         dle = self.ds.domain_left_edge.to("code_length")
         dre = self.ds.domain_right_edge.to("code_length")
         if np.any(pos.min(axis=0) < dle) or \
            np.any(pos.max(axis=0) > dre):
             raise YTDomainOverflow(pos.min(axis=0), pos.max(axis=0), dle,
                                    dre)
         regions.add_data_file(pos, data_file.file_id)
         morton[ind:ind + pos.shape[0]] = compute_morton(
             pos[:, 0], pos[:, 1], pos[:, 2], dle, dre)
     return morton
Ejemplo n.º 33
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 def _initialize_index(self, data_file, regions):
     pcount = data_file.header["num_halos"]
     morton = np.empty(pcount, dtype='uint64')
     mylog.debug("Initializing index % 5i (% 7i particles)",
                 data_file.file_id, pcount)
     if pcount == 0: return morton
     ind = 0
     with open(data_file.filename, "rb") as f:
         f.seek(data_file._position_offset, os.SEEK_SET)
         halos = np.fromfile(f, dtype=self._halo_dt, count = pcount)
         pos = np.empty((halos.size, 3), dtype="float64")
         # These positions are in Mpc, *not* "code" units
         pos = data_file.ds.arr(pos, "code_length")
         dx = np.finfo(halos['particle_position_x'].dtype).eps
         dx = 2.0*self.ds.quan(dx, "code_length")
         pos[:,0] = halos["particle_position_x"]
         pos[:,1] = halos["particle_position_y"]
         pos[:,2] = halos["particle_position_z"]
         # These are 32 bit numbers, so we give a little lee-way.
         # Otherwise, for big sets of particles, we often will bump into the
         # domain edges.  This helps alleviate that.
         np.clip(pos, self.ds.domain_left_edge + dx,
                      self.ds.domain_right_edge - dx, pos)
         del halos
         if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
            np.any(pos.max(axis=0) > self.ds.domain_right_edge):
             raise YTDomainOverflow(pos.min(axis=0),
                                    pos.max(axis=0),
                                    self.ds.domain_left_edge,
                                    self.ds.domain_right_edge)
         regions.add_data_file(pos, data_file.file_id)
         morton[ind:ind+pos.shape[0]] = compute_morton(
             pos[:,0], pos[:,1], pos[:,2],
             data_file.ds.domain_left_edge,
             data_file.ds.domain_right_edge)
     return morton
Ejemplo n.º 34
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    def _initialize_index(self, data_file, regions):
        pcount = sum(data_file.total_particles.values())
        morton = np.empty(pcount, dtype='uint64')
        if pcount == 0: return morton
        mylog.debug("Initializing index % 5i (% 7i particles)",
                    data_file.file_id, pcount)
        ind = 0
        with h5py.File(data_file.filename, "r") as f:
            if not f.keys(): return None
            dx = np.finfo(f["Group"]["GroupPos"].dtype).eps
            dx = 2.0*self.ds.quan(dx, "code_length")

            for ptype in data_file.ds.particle_types_raw:
                if data_file.total_particles[ptype] == 0: continue
                pos = f[ptype]["%sPos" % ptype].value.astype("float64")
                pos = np.resize(pos, (data_file.total_particles[ptype], 3))
                pos = data_file.ds.arr(pos, "code_length")
                
                # These are 32 bit numbers, so we give a little lee-way.
                # Otherwise, for big sets of particles, we often will bump into the
                # domain edges.  This helps alleviate that.
                np.clip(pos, self.ds.domain_left_edge + dx,
                             self.ds.domain_right_edge - dx, pos)
                if np.any(pos.min(axis=0) < self.ds.domain_left_edge) or \
                   np.any(pos.max(axis=0) > self.ds.domain_right_edge):
                    raise YTDomainOverflow(pos.min(axis=0),
                                           pos.max(axis=0),
                                           self.ds.domain_left_edge,
                                           self.ds.domain_right_edge)
                regions.add_data_file(pos, data_file.file_id)
                morton[ind:ind+pos.shape[0]] = compute_morton(
                    pos[:,0], pos[:,1], pos[:,2],
                    data_file.ds.domain_left_edge,
                    data_file.ds.domain_right_edge)
                ind += pos.shape[0]
        return morton
    def smooth(self, positions, fields = None, index_fields = None,
               method = None, create_octree = False, nneighbors = 64):
        r"""Operate on the mesh, in a particle-against-mesh fashion, with
        non-local input.

        This uses the octree indexing system to call a "smoothing" operation
        (defined in yt/geometry/particle_smooth.pyx) that can take input from
        several (non-local) particles and construct some value on the mesh.
        The canonical example is to conduct a smoothing kernel operation on the
        mesh.

        Parameters
        ----------
        positions : array_like (Nx3)
            The positions of all of the particles to be examined.  A new
            indexed octree will be constructed on these particles.
        fields : list of arrays
            All the necessary fields for computing the particle operation.  For
            instance, this might include mass, velocity, etc.  
        index_fields : list of arrays
            All of the fields defined on the mesh that may be used as input to
            the operation.
        method : string
            This is the "method name" which will be looked up in the
            `particle_smooth` namespace as `methodname_smooth`.  Current
            methods include `volume_weighted`, `nearest`, `idw`,
            `nth_neighbor`, and `density`.
        create_octree : bool
            Should we construct a new octree for indexing the particles?  In
            cases where we are applying an operation on a subset of the
            particles used to construct the mesh octree, this will ensure that
            we are able to find and identify all relevant particles.
        nneighbors : int, default 64
            The number of neighbors to examine during the process.

        Returns
        -------
        List of fortran-ordered, mesh-like arrays.
        """
        # Here we perform our particle deposition.
        positions.convert_to_units("code_length")
        if create_octree:
            morton = compute_morton(
                positions[:,0], positions[:,1], positions[:,2],
                self.ds.domain_left_edge,
                self.ds.domain_right_edge)
            morton.sort()
            particle_octree = ParticleOctreeContainer([1, 1, 1],
                self.ds.domain_left_edge,
                self.ds.domain_right_edge,
                over_refine = self._oref)
            # This should ensure we get everything within one neighbor of home.
            particle_octree.n_ref = nneighbors * 2
            particle_octree.add(morton)
            particle_octree.finalize()
            pdom_ind = particle_octree.domain_ind(self.selector)
        else:
            particle_octree = self.oct_handler
            pdom_ind = self.domain_ind
        if fields is None: fields = []
        if index_fields is None: index_fields = []
        cls = getattr(particle_smooth, "%s_smooth" % method, None)
        if cls is None:
            raise YTParticleDepositionNotImplemented(method)
        nz = self.nz
        mdom_ind = self.domain_ind
        nvals = (nz, nz, nz, (mdom_ind >= 0).sum())
        op = cls(nvals, len(fields), nneighbors)
        op.initialize()
        mylog.debug("Smoothing %s particles into %s Octs",
            positions.shape[0], nvals[-1])
        op.process_octree(self.oct_handler, mdom_ind, positions, 
            self.fcoords, fields,
            self.domain_id, self._domain_offset, self.ds.periodicity,
            index_fields, particle_octree, pdom_ind, self.ds.geometry)
        # If there are 0s in the smoothing field this will not throw an error, 
        # but silently return nans for vals where dividing by 0
        # Same as what is currently occurring, but suppressing the div by zero
        # error.
        with np.errstate(invalid='ignore'):
            vals = op.finalize()
        if vals is None: return
        if isinstance(vals, list):
            vals = [np.asfortranarray(v) for v in vals]
        else:
            vals = np.asfortranarray(vals)
        return vals
Ejemplo n.º 36
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    def particle_operation(self,
                           positions,
                           fields=None,
                           method=None,
                           nneighbors=64,
                           kernel_name='cubic'):
        r"""Operate on particles, in a particle-against-particle fashion.

        This uses the octree indexing system to call a "smoothing" operation
        (defined in yt/geometry/particle_smooth.pyx) that expects to be called
        in a particle-by-particle fashion.  For instance, the canonical example
        of this would be to compute the Nth nearest neighbor, or to compute the
        density for a given particle based on some kernel operation.

        Many of the arguments to this are identical to those used in the smooth
        and deposit functions.  Note that the `fields` argument must not be
        empty, as these fields will be modified in place.

        Parameters
        ----------
        positions : array_like (Nx3)
            The positions of all of the particles to be examined.  A new
            indexed octree will be constructed on these particles.
        fields : list of arrays
            All the necessary fields for computing the particle operation.  For
            instance, this might include mass, velocity, etc.  One of these
            will likely be modified in place.
        method : string
            This is the "method name" which will be looked up in the
            `particle_smooth` namespace as `methodname_smooth`.
        nneighbors : int, default 64
            The number of neighbors to examine during the process.
        kernel_name : string, default 'cubic'
            This is the name of the smoothing kernel to use. Current supported
            kernel names include `cubic`, `quartic`, `quintic`, `wendland2`,
            `wendland4`, and `wendland6`.

        Returns
        -------
        Nothing.

        """
        # Here we perform our particle deposition.
        positions.convert_to_units("code_length")
        morton = compute_morton(positions[:, 0], positions[:, 1],
                                positions[:, 2], self.ds.domain_left_edge,
                                self.ds.domain_right_edge)
        morton.sort()
        particle_octree = ParticleOctreeContainer([1, 1, 1],
                                                  self.ds.domain_left_edge,
                                                  self.ds.domain_right_edge,
                                                  over_refine=1)
        particle_octree.n_ref = nneighbors * 2
        particle_octree.add(morton)
        particle_octree.finalize()
        pdom_ind = particle_octree.domain_ind(self.selector)
        if fields is None: fields = []
        cls = getattr(particle_smooth, "%s_smooth" % method, None)
        if cls is None:
            raise YTParticleDepositionNotImplemented(method)
        nz = self.nz
        mdom_ind = self.domain_ind
        nvals = (nz, nz, nz, (mdom_ind >= 0).sum())
        op = cls(nvals, len(fields), nneighbors, kernel_name)
        op.initialize()
        mylog.debug("Smoothing %s particles into %s Octs", positions.shape[0],
                    nvals[-1])
        op.process_particles(particle_octree, pdom_ind, positions, fields,
                             self.domain_id, self._domain_offset,
                             self.ds.periodicity, self.ds.geometry)
        vals = op.finalize()
        if vals is None: return
        if isinstance(vals, list):
            vals = [np.asfortranarray(v) for v in vals]
        else:
            vals = np.asfortranarray(vals)
        return vals
Ejemplo n.º 37
0
    def smooth(self,
               positions,
               fields=None,
               index_fields=None,
               method=None,
               create_octree=False,
               nneighbors=64,
               kernel_name='cubic'):
        r"""Operate on the mesh, in a particle-against-mesh fashion, with
        non-local input.

        This uses the octree indexing system to call a "smoothing" operation
        (defined in yt/geometry/particle_smooth.pyx) that can take input from
        several (non-local) particles and construct some value on the mesh.
        The canonical example is to conduct a smoothing kernel operation on the
        mesh.

        Parameters
        ----------
        positions : array_like (Nx3)
            The positions of all of the particles to be examined.  A new
            indexed octree will be constructed on these particles.
        fields : list of arrays
            All the necessary fields for computing the particle operation.  For
            instance, this might include mass, velocity, etc.
        index_fields : list of arrays
            All of the fields defined on the mesh that may be used as input to
            the operation.
        method : string
            This is the "method name" which will be looked up in the
            `particle_smooth` namespace as `methodname_smooth`.  Current
            methods include `volume_weighted`, `nearest`, `idw`,
            `nth_neighbor`, and `density`.
        create_octree : bool
            Should we construct a new octree for indexing the particles?  In
            cases where we are applying an operation on a subset of the
            particles used to construct the mesh octree, this will ensure that
            we are able to find and identify all relevant particles.
        nneighbors : int, default 64
            The number of neighbors to examine during the process.
        kernel_name : string, default 'cubic'
            This is the name of the smoothing kernel to use. Current supported
            kernel names include `cubic`, `quartic`, `quintic`, `wendland2`,
            `wendland4`, and `wendland6`.

        Returns
        -------
        List of fortran-ordered, mesh-like arrays.
        """
        # Here we perform our particle deposition.
        positions.convert_to_units("code_length")
        if create_octree:
            morton = compute_morton(positions[:, 0], positions[:, 1],
                                    positions[:, 2], self.ds.domain_left_edge,
                                    self.ds.domain_right_edge)
            morton.sort()
            particle_octree = ParticleOctreeContainer(
                [1, 1, 1],
                self.ds.domain_left_edge,
                self.ds.domain_right_edge,
                over_refine=self._oref)
            # This should ensure we get everything within one neighbor of home.
            particle_octree.n_ref = nneighbors * 2
            particle_octree.add(morton)
            particle_octree.finalize()
            pdom_ind = particle_octree.domain_ind(self.selector)
        else:
            particle_octree = self.oct_handler
            pdom_ind = self.domain_ind
        if fields is None: fields = []
        if index_fields is None: index_fields = []
        cls = getattr(particle_smooth, "%s_smooth" % method, None)
        if cls is None:
            raise YTParticleDepositionNotImplemented(method)
        nz = self.nz
        mdom_ind = self.domain_ind
        nvals = (nz, nz, nz, (mdom_ind >= 0).sum())
        op = cls(nvals, len(fields), nneighbors, kernel_name)
        op.initialize()
        mylog.debug("Smoothing %s particles into %s Octs", positions.shape[0],
                    nvals[-1])
        # Pointer operations within 'process_octree' require arrays to be
        # contiguous cf. https://bitbucket.org/yt_analysis/yt/issues/1079
        fields = [np.ascontiguousarray(f, dtype="float64") for f in fields]
        op.process_octree(self.oct_handler, mdom_ind, positions, self.fcoords,
                          fields, self.domain_id, self._domain_offset,
                          self.ds.periodicity, index_fields, particle_octree,
                          pdom_ind, self.ds.geometry)
        # If there are 0s in the smoothing field this will not throw an error,
        # but silently return nans for vals where dividing by 0
        # Same as what is currently occurring, but suppressing the div by zero
        # error.
        with np.errstate(invalid='ignore'):
            vals = op.finalize()
        if vals is None: return
        if isinstance(vals, list):
            vals = [np.asfortranarray(v) for v in vals]
        else:
            vals = np.asfortranarray(vals)
        return vals
    def particle_operation(self, positions, fields = None,
            method = None, nneighbors = 64):
        r"""Operate on particles, in a particle-against-particle fashion.

        This uses the octree indexing system to call a "smoothing" operation
        (defined in yt/geometry/particle_smooth.pyx) that expects to be called
        in a particle-by-particle fashion.  For instance, the canonical example
        of this would be to compute the Nth nearest neighbor, or to compute the
        density for a given particle based on some kernel operation.

        Many of the arguments to this are identical to those used in the smooth
        and deposit functions.  Note that the `fields` argument must not be
        empty, as these fields will be modified in place.

        Parameters
        ----------
        positions : array_like (Nx3)
            The positions of all of the particles to be examined.  A new
            indexed octree will be constructed on these particles.
        fields : list of arrays
            All the necessary fields for computing the particle operation.  For
            instance, this might include mass, velocity, etc.  One of these
            will likely be modified in place.
        method : string
            This is the "method name" which will be looked up in the
            `particle_smooth` namespace as `methodname_smooth`.
        nneighbors : int, default 64
            The number of neighbors to examine during the process.

        Returns
        -------
        Nothing.

        """
        # Here we perform our particle deposition.
        positions.convert_to_units("code_length")
        morton = compute_morton(
            positions[:,0], positions[:,1], positions[:,2],
            self.ds.domain_left_edge,
            self.ds.domain_right_edge)
        morton.sort()
        particle_octree = ParticleOctreeContainer([1, 1, 1],
            self.ds.domain_left_edge,
            self.ds.domain_right_edge,
            over_refine = 1)
        particle_octree.n_ref = nneighbors * 2
        particle_octree.add(morton)
        particle_octree.finalize()
        pdom_ind = particle_octree.domain_ind(self.selector)
        if fields is None: fields = []
        cls = getattr(particle_smooth, "%s_smooth" % method, None)
        if cls is None:
            raise YTParticleDepositionNotImplemented(method)
        nz = self.nz
        mdom_ind = self.domain_ind
        nvals = (nz, nz, nz, (mdom_ind >= 0).sum())
        op = cls(nvals, len(fields), nneighbors)
        op.initialize()
        mylog.debug("Smoothing %s particles into %s Octs",
            positions.shape[0], nvals[-1])
        op.process_particles(particle_octree, pdom_ind, positions, 
            fields, self.domain_id, self._domain_offset, self.ds.periodicity,
            self.ds.geometry)
        vals = op.finalize()
        if vals is None: return
        if isinstance(vals, list):
            vals = [np.asfortranarray(v) for v in vals]
        else:
            vals = np.asfortranarray(vals)
        return vals