Example #1
0
 def astype(self, space, dtype, order, copy=True):
     # copy the general pattern of the strides
     # but make the array storage contiguous in memory
     shape = self.get_shape()
     strides = self.get_strides()
     if order not in (NPY.KEEPORDER, NPY.FORTRANORDER, NPY.CORDER):
         raise oefmt(space.w_ValueError, "Unknown order %d in astype", order)
     if len(strides) == 0:
         t_strides = []
         backstrides = []
     elif order in (NPY.FORTRANORDER, NPY.CORDER):
         t_strides, backstrides = calc_strides(shape, dtype, order)
     else:
         indx_array = range(len(strides))
         list_sorter = StrideSort(indx_array, strides, self.order)
         list_sorter.sort()
         t_elsize = dtype.elsize
         t_strides = strides[:]
         base = dtype.elsize
         for i in indx_array:
             t_strides[i] = base
             base *= shape[i]
         backstrides = calc_backstrides(t_strides, shape)
     order = support.get_order_as_CF(self.order, order)
     impl = ConcreteArray(shape, dtype, order, t_strides, backstrides)
     if copy:
         loop.setslice(space, impl.get_shape(), impl, self)
     return impl
Example #2
0
 def astype(self, space, dtype, order, copy=True):
     # copy the general pattern of the strides
     # but make the array storage contiguous in memory
     shape = self.get_shape()
     strides = self.get_strides()
     if order not in (NPY.KEEPORDER, NPY.FORTRANORDER, NPY.CORDER):
         raise oefmt(space.w_ValueError, "Unknown order %d in astype", order)
     if len(strides) == 0:
         t_strides = []
         backstrides = []
     elif order in (NPY.FORTRANORDER, NPY.CORDER):
         t_strides, backstrides = calc_strides(shape, dtype, order)
     else:
         indx_array = range(len(strides))
         list_sorter = StrideSort(indx_array, strides, self.order)
         list_sorter.sort()
         t_elsize = dtype.elsize
         t_strides = strides[:]
         base = dtype.elsize
         for i in indx_array:
             t_strides[i] = base
             base *= shape[i]
         backstrides = calc_backstrides(t_strides, shape)
     order = support.get_order_as_CF(self.order, order)
     impl = ConcreteArray(shape, dtype, order, t_strides, backstrides)
     if copy:
         loop.setslice(space, impl.get_shape(), impl, self)
     return impl
Example #3
0
 def reshape(self, orig_array, new_shape, order=NPY.ANYORDER):
     # Since we got to here, prod(new_shape) == self.size
     order = support.get_order_as_CF(self.order, order)
     new_strides = None
     if self.size == 0:
         new_strides, _ = calc_strides(new_shape, self.dtype, order)
     else:
         if len(self.get_shape()) == 0:
             new_strides = [self.dtype.elsize] * len(new_shape)
         else:
             new_strides = calc_new_strides(new_shape, self.get_shape(),
                                            self.get_strides(), order)
             if new_strides is None or len(new_strides) != len(new_shape):
                 return None
     if new_strides is not None:
         # We can create a view, strides somehow match up.
         new_backstrides = calc_backstrides(new_strides, new_shape)
         assert isinstance(orig_array, W_NDimArray) or orig_array is None
         return SliceArray(self.start, new_strides, new_backstrides,
                           new_shape, self, orig_array)
     return None
Example #4
0
 def reshape(self, orig_array, new_shape, order=NPY.ANYORDER):
     # Since we got to here, prod(new_shape) == self.size
     order = support.get_order_as_CF(self.order, order)
     new_strides = None
     if self.size == 0:
         new_strides, _ = calc_strides(new_shape, self.dtype, order)
     else:
         if len(self.get_shape()) == 0:
             new_strides = [self.dtype.elsize] * len(new_shape)
         else:
             new_strides = calc_new_strides(new_shape, self.get_shape(),
                                            self.get_strides(), order)
             if new_strides is None or len(new_strides) != len(new_shape):
                 return None
     if new_strides is not None:
         # We can create a view, strides somehow match up.
         new_backstrides = calc_backstrides(new_strides, new_shape)
         assert isinstance(orig_array, W_NDimArray) or orig_array is None
         return SliceArray(self.start, new_strides, new_backstrides,
                           new_shape, self, orig_array)
     return None
Example #5
0
    def __init__(self,
                 space,
                 w_seq,
                 w_flags,
                 w_op_flags,
                 w_op_dtypes,
                 w_casting,
                 w_op_axes,
                 w_itershape,
                 buffersize=0,
                 order=NPY.KEEPORDER,
                 allow_backward=True):
        self.external_loop = False
        self.buffered = False
        self.tracked_index = ''
        self.common_dtype = False
        self.delay_bufalloc = False
        self.grow_inner = False
        self.ranged = False
        self.refs_ok = False
        self.reduce_ok = False
        self.zerosize_ok = False
        self.index_iter = None
        self.done = False
        self.first_next = True
        self.op_axes = []
        self.allow_backward = allow_backward
        if not space.is_w(w_casting, space.w_None):
            self.casting = space.str_w(w_casting)
        else:
            self.casting = 'safe'
        # convert w_seq operands to a list of W_NDimArray
        if space.isinstance_w(w_seq, space.w_tuple) or \
           space.isinstance_w(w_seq, space.w_list):
            w_seq_as_list = space.listview(w_seq)
            self.seq = [
                convert_to_array(space, w_elem)
                if not space.is_none(w_elem) else None
                for w_elem in w_seq_as_list
            ]
        else:
            self.seq = [convert_to_array(space, w_seq)]
        if order == NPY.ANYORDER:
            # 'A' means "'F' order if all the arrays are Fortran contiguous,
            #            'C' order otherwise"
            order = NPY.CORDER
            for s in self.seq:
                if s and not (s.get_flags() & NPY.ARRAY_F_CONTIGUOUS):
                    break
                else:
                    order = NPY.FORTRANORDER
        elif order == NPY.KEEPORDER:
            # 'K' means "as close to the order the array elements appear in
            #     memory as possible", so match self.order to seq.order
            order = NPY.CORDER
            for s in self.seq:
                if s and not (s.get_order() == NPY.FORTRANORDER):
                    break
                else:
                    order = NPY.FORTRANORDER
        self.order = order
        parse_func_flags(space, self, w_flags)
        self.op_flags = parse_op_arg(space, 'op_flags', w_op_flags,
                                     len(self.seq), parse_op_flag)
        # handle w_op_axes
        oa_ndim = -1
        if not space.is_none(w_op_axes):
            oa_ndim = self.set_op_axes(space, w_op_axes)
        self.ndim = calculate_ndim(self.seq, oa_ndim)

        # handle w_op_dtypes part 1: creating self.dtypes list from input
        if not space.is_none(w_op_dtypes):
            w_seq_as_list = space.listview(w_op_dtypes)
            self.dtypes = [
                decode_w_dtype(space, w_elem) for w_elem in w_seq_as_list
            ]
            if len(self.dtypes) != len(self.seq):
                raise oefmt(
                    space.w_ValueError,
                    "op_dtypes must be a tuple/list matching the number of ops"
                )
        else:
            self.dtypes = []

        # handle None or writable operands, calculate my shape
        outargs = [
            i for i in range(len(self.seq))
            if self.seq[i] is None or self.op_flags[i].rw == 'w'
        ]
        if len(outargs) > 0:
            out_shape = shape_agreement_multiple(
                space, [self.seq[i] for i in outargs])
        else:
            out_shape = None
        if space.isinstance_w(w_itershape, space.w_tuple) or \
           space.isinstance_w(w_itershape, space.w_list):
            self.shape = [space.int_w(i) for i in space.listview(w_itershape)]
        else:
            self.shape = shape_agreement_multiple(space,
                                                  self.seq,
                                                  shape=out_shape)
        if len(outargs) > 0:
            # Make None operands writeonly and flagged for allocation
            if len(self.dtypes) > 0:
                out_dtype = self.dtypes[outargs[0]]
            else:
                out_dtype = None
                for i in range(len(self.seq)):
                    if self.seq[i] is None:
                        self.op_flags[i].allocate = True
                        continue
                    if self.op_flags[i].rw == 'w':
                        continue
                    out_dtype = find_binop_result_dtype(
                        space, self.seq[i].get_dtype(), out_dtype)
            for i in outargs:
                if self.seq[i] is None:
                    # XXX can we postpone allocation to later?
                    self.seq[i] = W_NDimArray.from_shape(
                        space, self.shape, out_dtype)
                else:
                    if not self.op_flags[i].broadcast:
                        # Raises if output cannot be broadcast
                        try:
                            shape_agreement(space, self.shape, self.seq[i],
                                            False)
                        except OperationError as e:
                            raise oefmt(
                                space.w_ValueError, "non-broadcastable"
                                " output operand with shape %s doesn't match "
                                "the broadcast shape %s",
                                str(self.seq[i].get_shape()), str(self.shape))

        if self.tracked_index != "":
            order = self.order
            if order == NPY.KEEPORDER:
                order = self.seq[0].implementation.order
            if self.tracked_index == "multi":
                backward = False
            else:
                backward = ((order == NPY.CORDER and self.tracked_index != 'C')
                            or (order == NPY.FORTRANORDER
                                and self.tracked_index != 'F'))
            self.index_iter = IndexIterator(self.shape, backward=backward)

        # handle w_op_dtypes part 2: copy where needed if possible
        if len(self.dtypes) > 0:
            for i in range(len(self.seq)):
                self_d = self.dtypes[i]
                seq_d = self.seq[i].get_dtype()
                if not self_d:
                    self.dtypes[i] = seq_d
                elif self_d != seq_d:
                    impl = self.seq[i].implementation
                    if self.buffered or 'r' in self.op_flags[i].tmp_copy:
                        if not can_cast_array(space, self.seq[i], self_d,
                                              self.casting):
                            raise oefmt(
                                space.w_TypeError, "Iterator operand %d"
                                " dtype could not be cast from %s to %s"
                                " according to the rule '%s'", i,
                                space.str_w(seq_d.descr_repr(space)),
                                space.str_w(self_d.descr_repr(space)),
                                self.casting)
                        order = support.get_order_as_CF(impl.order, self.order)
                        new_impl = impl.astype(space, self_d,
                                               order).copy(space)
                        self.seq[i] = W_NDimArray(new_impl)
                    else:
                        raise oefmt(
                            space.w_TypeError, "Iterator "
                            "operand required copying or buffering, "
                            "but neither copying nor buffering was "
                            "enabled")
                    if 'w' in self.op_flags[i].rw:
                        if not can_cast_type(space, self_d, seq_d,
                                             self.casting):
                            raise oefmt(
                                space.w_TypeError, "Iterator"
                                " requested dtype could not be cast from "
                                " %s to %s, the operand %d dtype, accord"
                                "ing to the rule '%s'",
                                space.str_w(self_d.descr_repr(space)),
                                space.str_w(seq_d.descr_repr(space)), i,
                                self.casting)
        elif self.buffered and not (self.external_loop and len(self.seq) < 2):
            for i in range(len(self.seq)):
                if i not in outargs:
                    self.seq[i] = self.seq[i].descr_copy(space,
                                                         w_order=space.wrap(
                                                             self.order))
            self.dtypes = [s.get_dtype() for s in self.seq]
        else:
            #copy them from seq
            self.dtypes = [s.get_dtype() for s in self.seq]

        # create an iterator for each operand
        self.iters = []
        for i in range(len(self.seq)):
            it = self.get_iter(space, i)
            it.contiguous = False
            self.iters.append((it, it.reset()))

        if self.external_loop:
            coalesce_axes(self, space)
Example #6
0
    def __init__(
        self,
        space,
        w_seq,
        w_flags,
        w_op_flags,
        w_op_dtypes,
        w_casting,
        w_op_axes,
        w_itershape,
        buffersize=0,
        order=NPY.KEEPORDER,
        allow_backward=True,
    ):
        self.external_loop = False
        self.buffered = False
        self.tracked_index = ""
        self.common_dtype = False
        self.delay_bufalloc = False
        self.grow_inner = False
        self.ranged = False
        self.refs_ok = False
        self.reduce_ok = False
        self.zerosize_ok = False
        self.index_iter = None
        self.done = False
        self.first_next = True
        self.op_axes = []
        self.allow_backward = allow_backward
        if not space.is_w(w_casting, space.w_None):
            self.casting = space.str_w(w_casting)
        else:
            self.casting = "safe"
        # convert w_seq operands to a list of W_NDimArray
        if space.isinstance_w(w_seq, space.w_tuple) or space.isinstance_w(w_seq, space.w_list):
            w_seq_as_list = space.listview(w_seq)
            self.seq = [
                convert_to_array(space, w_elem) if not space.is_none(w_elem) else None for w_elem in w_seq_as_list
            ]
        else:
            self.seq = [convert_to_array(space, w_seq)]
        if order == NPY.ANYORDER:
            # 'A' means "'F' order if all the arrays are Fortran contiguous,
            #            'C' order otherwise"
            order = NPY.CORDER
            for s in self.seq:
                if s and not (s.get_flags() & NPY.ARRAY_F_CONTIGUOUS):
                    break
                else:
                    order = NPY.FORTRANORDER
        elif order == NPY.KEEPORDER:
            # 'K' means "as close to the order the array elements appear in
            #     memory as possible", so match self.order to seq.order
            order = NPY.CORDER
            for s in self.seq:
                if s and not (s.get_order() == NPY.FORTRANORDER):
                    break
                else:
                    order = NPY.FORTRANORDER
        self.order = order
        parse_func_flags(space, self, w_flags)
        self.op_flags = parse_op_arg(space, "op_flags", w_op_flags, len(self.seq), parse_op_flag)
        # handle w_op_axes
        oa_ndim = -1
        if not space.is_none(w_op_axes):
            oa_ndim = self.set_op_axes(space, w_op_axes)
        self.ndim = calculate_ndim(self.seq, oa_ndim)

        # handle w_op_dtypes part 1: creating self.dtypes list from input
        if not space.is_none(w_op_dtypes):
            w_seq_as_list = space.listview(w_op_dtypes)
            self.dtypes = [decode_w_dtype(space, w_elem) for w_elem in w_seq_as_list]
            if len(self.dtypes) != len(self.seq):
                raise oefmt(space.w_ValueError, "op_dtypes must be a tuple/list matching the number of ops")
        else:
            self.dtypes = []

        # handle None or writable operands, calculate my shape
        outargs = [i for i in range(len(self.seq)) if self.seq[i] is None or self.op_flags[i].rw == "w"]
        if len(outargs) > 0:
            out_shape = shape_agreement_multiple(space, [self.seq[i] for i in outargs])
        else:
            out_shape = None
        if space.isinstance_w(w_itershape, space.w_tuple) or space.isinstance_w(w_itershape, space.w_list):
            self.shape = [space.int_w(i) for i in space.listview(w_itershape)]
        else:
            self.shape = shape_agreement_multiple(space, self.seq, shape=out_shape)
        if len(outargs) > 0:
            # Make None operands writeonly and flagged for allocation
            if len(self.dtypes) > 0:
                out_dtype = self.dtypes[outargs[0]]
            else:
                out_dtype = None
                for i in range(len(self.seq)):
                    if self.seq[i] is None:
                        self.op_flags[i].allocate = True
                        continue
                    if self.op_flags[i].rw == "w":
                        continue
                    out_dtype = find_binop_result_dtype(space, self.seq[i].get_dtype(), out_dtype)
            for i in outargs:
                if self.seq[i] is None:
                    # XXX can we postpone allocation to later?
                    self.seq[i] = W_NDimArray.from_shape(space, self.shape, out_dtype)
                else:
                    if not self.op_flags[i].broadcast:
                        # Raises if output cannot be broadcast
                        try:
                            shape_agreement(space, self.shape, self.seq[i], False)
                        except OperationError as e:
                            raise oefmt(
                                space.w_ValueError,
                                "non-broadcastable"
                                " output operand with shape %s doesn't match "
                                "the broadcast shape %s",
                                str(self.seq[i].get_shape()),
                                str(self.shape),
                            )

        if self.tracked_index != "":
            order = self.order
            if order == NPY.KEEPORDER:
                order = self.seq[0].implementation.order
            if self.tracked_index == "multi":
                backward = False
            else:
                backward = (order == NPY.CORDER and self.tracked_index != "C") or (
                    order == NPY.FORTRANORDER and self.tracked_index != "F"
                )
            self.index_iter = IndexIterator(self.shape, backward=backward)

        # handle w_op_dtypes part 2: copy where needed if possible
        if len(self.dtypes) > 0:
            for i in range(len(self.seq)):
                self_d = self.dtypes[i]
                seq_d = self.seq[i].get_dtype()
                if not self_d:
                    self.dtypes[i] = seq_d
                elif self_d != seq_d:
                    impl = self.seq[i].implementation
                    if self.buffered or "r" in self.op_flags[i].tmp_copy:
                        if not can_cast_array(space, self.seq[i], self_d, self.casting):
                            raise oefmt(
                                space.w_TypeError,
                                "Iterator operand %d"
                                " dtype could not be cast from %s to %s"
                                " according to the rule '%s'",
                                i,
                                space.str_w(seq_d.descr_repr(space)),
                                space.str_w(self_d.descr_repr(space)),
                                self.casting,
                            )
                        order = support.get_order_as_CF(impl.order, self.order)
                        new_impl = impl.astype(space, self_d, order).copy(space)
                        self.seq[i] = W_NDimArray(new_impl)
                    else:
                        raise oefmt(
                            space.w_TypeError,
                            "Iterator "
                            "operand required copying or buffering, "
                            "but neither copying nor buffering was "
                            "enabled",
                        )
                    if "w" in self.op_flags[i].rw:
                        if not can_cast_type(space, self_d, seq_d, self.casting):
                            raise oefmt(
                                space.w_TypeError,
                                "Iterator"
                                " requested dtype could not be cast from "
                                " %s to %s, the operand %d dtype, accord"
                                "ing to the rule '%s'",
                                space.str_w(self_d.descr_repr(space)),
                                space.str_w(seq_d.descr_repr(space)),
                                i,
                                self.casting,
                            )
        elif self.buffered and not (self.external_loop and len(self.seq) < 2):
            for i in range(len(self.seq)):
                if i not in outargs:
                    self.seq[i] = self.seq[i].descr_copy(space, w_order=space.wrap(self.order))
            self.dtypes = [s.get_dtype() for s in self.seq]
        else:
            # copy them from seq
            self.dtypes = [s.get_dtype() for s in self.seq]

        # create an iterator for each operand
        self.iters = []
        for i in range(len(self.seq)):
            it = self.get_iter(space, i)
            it.contiguous = False
            self.iters.append((it, it.reset()))

        if self.external_loop:
            coalesce_axes(self, space)
Example #7
0
def _array(space,
           w_object,
           w_dtype=None,
           copy=True,
           w_order=None,
           subok=False):

    from pypy.module.micronumpy.boxes import W_GenericBox
    # numpy testing calls array(type(array([]))) and expects a ValueError
    if space.isinstance_w(w_object, space.w_type):
        raise oefmt(space.w_ValueError,
                    "cannot create ndarray from type instance")
    # for anything that isn't already an array, try __array__ method first
    dtype = descriptor.decode_w_dtype(space, w_dtype)
    if not isinstance(w_object, W_NDimArray):
        w_array = try_array_method(space, w_object, w_dtype)
        if w_array is None:
            if (not space.isinstance_w(w_object, space.w_bytes)
                    and not space.isinstance_w(w_object, space.w_unicode)
                    and not isinstance(w_object, W_GenericBox)):
                # use buffer interface
                w_object = _array_from_buffer_3118(space, w_object, dtype)
        else:
            # continue with w_array, but do further operations in place
            w_object = w_array
            copy = False
            dtype = w_object.get_dtype()
    if not isinstance(w_object, W_NDimArray):
        w_array, _copy = try_interface_method(space, w_object, copy)
        if w_array is not None:
            w_object = w_array
            copy = _copy
            dtype = w_object.get_dtype()

    if isinstance(w_object, W_NDimArray):
        npy_order = order_converter(space, w_order, NPY.ANYORDER)
        if (dtype is None or w_object.get_dtype() is dtype) and (
                subok or type(w_object) is W_NDimArray):
            flags = w_object.get_flags()
            must_copy = copy
            must_copy |= (npy_order == NPY.CORDER
                          and not flags & NPY.ARRAY_C_CONTIGUOUS)
            must_copy |= (npy_order == NPY.FORTRANORDER
                          and not flags & NPY.ARRAY_F_CONTIGUOUS)
            if must_copy:
                return w_object.descr_copy(space, space.newint(npy_order))
            else:
                return w_object
        if subok and not type(w_object) is W_NDimArray:
            raise oefmt(space.w_NotImplementedError,
                        "array(..., subok=True) only partially implemented")
        # we have a ndarray, but need to copy or change dtype
        if dtype is None:
            dtype = w_object.get_dtype()
        if dtype != w_object.get_dtype():
            # silently reject the copy value
            copy = True
        if copy:
            shape = w_object.get_shape()
            order = support.get_order_as_CF(w_object.get_order(), npy_order)
            w_arr = W_NDimArray.from_shape(space, shape, dtype, order=order)
            if support.product(shape) == 1:
                w_arr.set_scalar_value(
                    dtype.coerce(space, w_object.implementation.getitem(0)))
            else:
                loop.setslice(space, shape, w_arr.implementation,
                              w_object.implementation)
            return w_arr
        else:
            imp = w_object.implementation
            w_base = w_object
            sz = w_base.get_size() * dtype.elsize
            if imp.base() is not None:
                w_base = imp.base()
                if type(w_base) is W_NDimArray:
                    sz = w_base.get_size() * dtype.elsize
                else:
                    # this must succeed (mmap, buffer, ...)
                    sz = space.int_w(space.call_method(w_base, 'size'))
            with imp as storage:
                return W_NDimArray.from_shape_and_storage(space,
                                                          w_object.get_shape(),
                                                          storage,
                                                          dtype,
                                                          storage_bytes=sz,
                                                          w_base=w_base,
                                                          strides=imp.strides,
                                                          start=imp.start)
    else:
        # not an array
        npy_order = order_converter(space, w_order, NPY.CORDER)
        shape, elems_w = find_shape_and_elems(space, w_object, dtype)
    if dtype is None and space.isinstance_w(w_object, space.w_buffer):
        dtype = descriptor.get_dtype_cache(space).w_uint8dtype
    if dtype is None or (dtype.is_str_or_unicode() and dtype.elsize < 1):
        dtype = find_dtype_for_seq(space, elems_w, dtype)

    w_arr = W_NDimArray.from_shape(space, shape, dtype, order=npy_order)
    if support.product(
            shape) == 1:  # safe from overflow since from_shape checks
        w_arr.set_scalar_value(dtype.coerce(space, elems_w[0]))
    else:
        loop.assign(space, w_arr, elems_w)
    return w_arr
Example #8
0
def _array(space, w_object, w_dtype=None, copy=True, w_order=None, subok=False):

    from pypy.module.micronumpy.boxes import W_GenericBox
    # numpy testing calls array(type(array([]))) and expects a ValueError
    if space.isinstance_w(w_object, space.w_type):
        raise oefmt(space.w_ValueError, "cannot create ndarray from type instance")
    # for anything that isn't already an array, try __array__ method first
    dtype = descriptor.decode_w_dtype(space, w_dtype)
    if not isinstance(w_object, W_NDimArray):
        w_array = try_array_method(space, w_object, w_dtype)
        if w_array is None:
            if (    not space.isinstance_w(w_object, space.w_str) and 
                    not space.isinstance_w(w_object, space.w_unicode) and
                    not isinstance(w_object, W_GenericBox)):
                # use buffer interface
                w_object = _array_from_buffer_3118(space, w_object, dtype)
        else:
            # continue with w_array, but do further operations in place
            w_object = w_array
            copy = False
            dtype = w_object.get_dtype()
    if not isinstance(w_object, W_NDimArray):
        w_array, _copy = try_interface_method(space, w_object, copy)
        if w_array is not None:
            w_object = w_array
            copy = _copy
            dtype = w_object.get_dtype()

    if isinstance(w_object, W_NDimArray):
        npy_order = order_converter(space, w_order, NPY.ANYORDER)
        if (dtype is None or w_object.get_dtype() is dtype) and (subok or
                type(w_object) is W_NDimArray):
            flags = w_object.get_flags()
            must_copy = copy
            must_copy |= (npy_order == NPY.CORDER and not flags & NPY.ARRAY_C_CONTIGUOUS)
            must_copy |= (npy_order == NPY.FORTRANORDER and not flags & NPY.ARRAY_F_CONTIGUOUS)
            if must_copy:
                return w_object.descr_copy(space, space.wrap(npy_order))
            else:
                return w_object
        if subok and not type(w_object) is W_NDimArray:
            raise oefmt(space.w_NotImplementedError,
                "array(..., subok=True) only partially implemented")
        # we have a ndarray, but need to copy or change dtype
        if dtype is None:
            dtype = w_object.get_dtype()
        if dtype != w_object.get_dtype():
            # silently reject the copy value
            copy = True
        if copy:
            shape = w_object.get_shape()
            order = support.get_order_as_CF(w_object.get_order(), npy_order)
            w_arr = W_NDimArray.from_shape(space, shape, dtype, order=order)
            if support.product(shape) == 1:
                w_arr.set_scalar_value(dtype.coerce(space,
                        w_object.implementation.getitem(0)))
            else:
                loop.setslice(space, shape, w_arr.implementation, w_object.implementation)
            return w_arr
        else:
            imp = w_object.implementation
            w_base = w_object
            sz = w_base.get_size() * dtype.elsize
            if imp.base() is not None:
                w_base = imp.base()
                if type(w_base) is W_NDimArray:
                    sz = w_base.get_size() * dtype.elsize
                else:
                    # this must succeed (mmap, buffer, ...)
                    sz = space.int_w(space.call_method(w_base, 'size'))
            with imp as storage:
                return W_NDimArray.from_shape_and_storage(space,
                    w_object.get_shape(), storage, dtype, storage_bytes=sz,
                    w_base=w_base, strides=imp.strides, start=imp.start)
    else:
        # not an array
        npy_order = order_converter(space, w_order, NPY.CORDER)
        shape, elems_w = find_shape_and_elems(space, w_object, dtype)
    if dtype is None and space.isinstance_w(w_object, space.w_buffer):
        dtype = descriptor.get_dtype_cache(space).w_uint8dtype
    if dtype is None or (dtype.is_str_or_unicode() and dtype.elsize < 1):
        dtype = find_dtype_for_seq(space, elems_w, dtype)

    w_arr = W_NDimArray.from_shape(space, shape, dtype, order=npy_order)
    if support.product(shape) == 1: # safe from overflow since from_shape checks
        w_arr.set_scalar_value(dtype.coerce(space, elems_w[0]))
    else:
        loop.assign(space, w_arr, elems_w)
    return w_arr