示例#1
0
    def _setup_transfers(group, recurse=True):
        """
        Compute all transfers that are owned by our parent group.

        Parameters
        ----------
        group : <Group>
            Parent group.
        recurse : bool
            Whether to call this method in subsystems.
        """
        group._transfers = {}
        iproc = group.comm.rank
        rev = group._mode == 'rev' or group._mode == 'auto'

        def merge(indices_list):
            if len(indices_list) > 0:
                return np.concatenate(indices_list)
            else:
                return _empty_idx_array

        if recurse:
            for subsys in group._subgroups_myproc:
                subsys._setup_transfers(recurse)

        # Pre-compute map from abs_names to the index of the containing subsystem
        abs2isub = {}
        for subsys, isub in zip(group._subsystems_myproc,
                                group._subsystems_myproc_inds):
            for type_ in ['input', 'output']:
                for abs_name in subsys._var_allprocs_abs_names[type_]:
                    abs2isub[abs_name] = isub

        abs2meta = group._var_abs2meta
        allprocs_abs2meta = group._var_allprocs_abs2meta

        transfers = group._transfers
        vectors = group._vectors
        offsets = _global2local_offsets(group._get_var_offsets())

        for vec_name in group._lin_rel_vec_name_list:
            relvars, _ = group._relevant[vec_name]['@all']
            relvars_in = relvars['input']
            relvars_out = relvars['output']

            # Initialize empty lists for the transfer indices
            nsub_allprocs = len(group._subsystems_allprocs)
            xfer_in = []
            xfer_out = []
            fwd_xfer_in = [[] for i in range(nsub_allprocs)]
            fwd_xfer_out = [[] for i in range(nsub_allprocs)]
            if rev:
                rev_xfer_in = [[] for i in range(nsub_allprocs)]
                rev_xfer_out = [[] for i in range(nsub_allprocs)]

            allprocs_abs2idx = group._var_allprocs_abs2idx[vec_name]
            sizes_in = group._var_sizes[vec_name]['input']
            sizes_out = group._var_sizes[vec_name]['output']
            offsets_in = offsets[vec_name]['input']
            offsets_out = offsets[vec_name]['output']

            # Loop through all explicit / implicit connections owned by this system
            for abs_in, abs_out in iteritems(group._conn_abs_in2out):
                if abs_out not in relvars_out or abs_in not in relvars_in:
                    continue

                # Only continue if the input exists on this processor
                if abs_in in abs2meta and abs_in in relvars['input']:

                    # Get meta
                    meta_in = abs2meta[abs_in]
                    meta_out = allprocs_abs2meta[abs_out]

                    idx_in = allprocs_abs2idx[abs_in]
                    idx_out = allprocs_abs2idx[abs_out]

                    # Read in and process src_indices
                    shape_in = meta_in['shape']
                    shape_out = meta_out['shape']
                    global_size_out = meta_out['global_size']
                    src_indices = meta_in['src_indices']
                    if src_indices is None:
                        pass
                    elif src_indices.ndim == 1:
                        src_indices = convert_neg(src_indices, global_size_out)
                    else:
                        if len(shape_out
                               ) == 1 or shape_in == src_indices.shape:
                            src_indices = src_indices.flatten()
                            src_indices = convert_neg(src_indices,
                                                      global_size_out)
                        else:
                            # TODO: this duplicates code found
                            # in System._setup_scaling.
                            entries = [list(range(x)) for x in shape_in]
                            cols = np.vstack(src_indices[i]
                                             for i in product(*entries))
                            dimidxs = [
                                convert_neg(cols[:, i], shape_out[i])
                                for i in range(cols.shape[1])
                            ]
                            src_indices = np.ravel_multi_index(
                                dimidxs, shape_out)

                    # 1. Compute the output indices
                    offset = offsets_out[iproc, idx_out]
                    if src_indices is None:
                        output_inds = np.arange(offset,
                                                offset + meta_in['size'],
                                                dtype=INT_DTYPE)
                    else:
                        output_inds = src_indices + offset

                    # 2. Compute the input indices
                    input_inds = np.arange(offsets_in[iproc, idx_in],
                                           offsets_in[iproc, idx_in] +
                                           sizes_in[iproc, idx_in],
                                           dtype=INT_DTYPE)

                    # Now the indices are ready - input_inds, output_inds
                    xfer_in.append(input_inds)
                    xfer_out.append(output_inds)

                    isub = abs2isub[abs_in]
                    fwd_xfer_in[isub].append(input_inds)
                    fwd_xfer_out[isub].append(output_inds)
                    if rev and abs_out in abs2isub:
                        isub = abs2isub[abs_out]
                        rev_xfer_in[isub].append(input_inds)
                        rev_xfer_out[isub].append(output_inds)

            xfer_in = merge(xfer_in)
            xfer_out = merge(xfer_out)
            for isub in range(nsub_allprocs):
                fwd_xfer_in[isub] = merge(fwd_xfer_in[isub])
                fwd_xfer_out[isub] = merge(fwd_xfer_out[isub])
                if rev:
                    rev_xfer_in[isub] = merge(rev_xfer_in[isub])
                    rev_xfer_out[isub] = merge(rev_xfer_out[isub])

            out_vec = vectors['output'][vec_name]

            transfers[vec_name] = {}
            xfer_all = DefaultTransfer(vectors['input'][vec_name], out_vec,
                                       xfer_in, xfer_out, group.comm)
            transfers[vec_name]['fwd', None] = xfer_all
            if rev:
                transfers[vec_name]['rev', None] = xfer_all
            for isub in range(nsub_allprocs):
                transfers[vec_name]['fwd', isub] = DefaultTransfer(
                    vectors['input'][vec_name], vectors['output'][vec_name],
                    fwd_xfer_in[isub], fwd_xfer_out[isub], group.comm)
                if rev:
                    transfers[vec_name]['rev', isub] = DefaultTransfer(
                        vectors['input'][vec_name],
                        vectors['output'][vec_name], rev_xfer_in[isub],
                        rev_xfer_out[isub], group.comm)

        transfers['nonlinear'] = transfers['linear']
示例#2
0
    def _setup_transfers(group, recurse=True):
        """
        Compute all transfers that are owned by our parent group.

        Parameters
        ----------
        group : <Group>
            Parent group.
        recurse : bool
            Whether to call this method in subsystems.
        """
        group._transfers = {}
        iproc = group.comm.rank
        rev = group._mode == 'rev' or group._mode == 'auto'

        def merge(indices_list):
            if len(indices_list) > 0:
                return np.concatenate(indices_list)
            else:
                return _empty_idx_array

        if recurse:
            for subsys in group._subgroups_myproc:
                subsys._setup_transfers(recurse)

        # Pre-compute map from abs_names to the index of the containing subsystem
        abs2isub = {}
        for subsys, isub in zip(group._subsystems_myproc, group._subsystems_myproc_inds):
            for type_ in ['input', 'output']:
                for abs_name in subsys._var_allprocs_abs_names[type_]:
                    abs2isub[abs_name] = isub

        abs2meta = group._var_abs2meta
        allprocs_abs2meta = group._var_allprocs_abs2meta

        transfers = group._transfers
        vectors = group._vectors
        offsets = _global2local_offsets(group._get_var_offsets())

        vec_names = group._lin_rel_vec_name_list if group._use_derivatives else group._vec_names

        for vec_name in vec_names:
            relvars, _ = group._relevant[vec_name]['@all']
            relvars_in = relvars['input']
            relvars_out = relvars['output']

            # Initialize empty lists for the transfer indices
            nsub_allprocs = len(group._subsystems_allprocs)
            xfer_in = []
            xfer_out = []
            fwd_xfer_in = [[] for i in range(nsub_allprocs)]
            fwd_xfer_out = [[] for i in range(nsub_allprocs)]
            if rev:
                rev_xfer_in = [[] for i in range(nsub_allprocs)]
                rev_xfer_out = [[] for i in range(nsub_allprocs)]

            allprocs_abs2idx = group._var_allprocs_abs2idx[vec_name]
            sizes_in = group._var_sizes[vec_name]['input']
            sizes_out = group._var_sizes[vec_name]['output']
            offsets_in = offsets[vec_name]['input']
            offsets_out = offsets[vec_name]['output']

            # Loop through all explicit / implicit connections owned by this system
            for abs_in, abs_out in iteritems(group._conn_abs_in2out):
                if abs_out not in relvars_out or abs_in not in relvars_in:
                    continue

                # Only continue if the input exists on this processor
                if abs_in in abs2meta and abs_in in relvars['input']:

                    # Get meta
                    meta_in = abs2meta[abs_in]
                    meta_out = allprocs_abs2meta[abs_out]

                    idx_in = allprocs_abs2idx[abs_in]
                    idx_out = allprocs_abs2idx[abs_out]

                    # Read in and process src_indices
                    src_indices = meta_in['src_indices']
                    if src_indices is None:
                        pass
                    elif src_indices.ndim == 1:
                        src_indices = convert_neg(src_indices, meta_out['global_size'])
                    else:
                        src_indices = _flatten_src_indices(src_indices, meta_in['shape'],
                                                           meta_out['global_shape'],
                                                           meta_out['global_size'])

                    # 1. Compute the output indices
                    offset = offsets_out[iproc, idx_out]
                    if src_indices is None:
                        output_inds = np.arange(offset, offset + meta_in['size'], dtype=INT_DTYPE)
                    else:
                        output_inds = src_indices + offset

                    # 2. Compute the input indices
                    input_inds = np.arange(offsets_in[iproc, idx_in],
                                           offsets_in[iproc, idx_in] +
                                           sizes_in[iproc, idx_in], dtype=INT_DTYPE)

                    # Now the indices are ready - input_inds, output_inds
                    xfer_in.append(input_inds)
                    xfer_out.append(output_inds)

                    isub = abs2isub[abs_in]
                    fwd_xfer_in[isub].append(input_inds)
                    fwd_xfer_out[isub].append(output_inds)
                    if rev and abs_out in abs2isub:
                        isub = abs2isub[abs_out]
                        rev_xfer_in[isub].append(input_inds)
                        rev_xfer_out[isub].append(output_inds)

            xfer_in = merge(xfer_in)
            xfer_out = merge(xfer_out)
            for isub in range(nsub_allprocs):
                fwd_xfer_in[isub] = merge(fwd_xfer_in[isub])
                fwd_xfer_out[isub] = merge(fwd_xfer_out[isub])
                if rev:
                    rev_xfer_in[isub] = merge(rev_xfer_in[isub])
                    rev_xfer_out[isub] = merge(rev_xfer_out[isub])

            out_vec = vectors['output'][vec_name]

            transfers[vec_name] = {}
            xfer_all = DefaultTransfer(vectors['input'][vec_name], out_vec,
                                       xfer_in, xfer_out, group.comm)
            transfers[vec_name]['fwd', None] = xfer_all
            if rev:
                transfers[vec_name]['rev', None] = xfer_all
            for isub in range(nsub_allprocs):
                transfers[vec_name]['fwd', isub] = DefaultTransfer(
                    vectors['input'][vec_name], vectors['output'][vec_name],
                    fwd_xfer_in[isub], fwd_xfer_out[isub], group.comm)
                if rev:
                    transfers[vec_name]['rev', isub] = DefaultTransfer(
                        vectors['input'][vec_name], vectors['output'][vec_name],
                        rev_xfer_in[isub], rev_xfer_out[isub], group.comm)

        if group._use_derivatives:
            transfers['nonlinear'] = transfers['linear']
示例#3
0
    def _setup_transfers(group):
        """
        Compute all transfers that are owned by our parent group.

        Parameters
        ----------
        group : <Group>
            Parent group.
        """
        iproc = group.comm.rank
        rev = group._mode == 'rev' or group._mode == 'auto'

        for subsys in group._subgroups_myproc:
            subsys._setup_transfers()

        abs2meta = group._var_abs2meta
        allprocs_abs2meta_out = group._var_allprocs_abs2meta['output']

        group._transfers = transfers = {}
        vectors = group._vectors
        offsets = _global2local_offsets(group._get_var_offsets())

        vec_names = group._lin_rel_vec_name_list if group._use_derivatives else group._vec_names
        allsubs = group._subsystems_allprocs

        mypathlen = len(group.pathname + '.' if group.pathname else '')

        for vec_name in vec_names:
            relvars, _ = group._relevant[vec_name]['@all']
            relvars_in = relvars['input']
            relvars_out = relvars['output']

            # Initialize empty lists for the transfer indices
            nsub_allprocs = len(allsubs)
            xfer_in = []
            xfer_out = []
            fwd_xfer_in = defaultdict(list)
            fwd_xfer_out = defaultdict(list)
            if rev:
                rev_xfer_in = defaultdict(list)
                rev_xfer_out = defaultdict(list)

            allprocs_abs2idx = group._var_allprocs_abs2idx[vec_name]
            sizes_in = group._var_sizes[vec_name]['input']
            sizes_out = group._var_sizes[vec_name]['output']
            offsets_in = offsets[vec_name]['input']
            offsets_out = offsets[vec_name]['output']

            # Loop through all connections owned by this group
            for abs_in, abs_out in group._conn_abs_in2out.items():
                if abs_out not in relvars_out or abs_in not in relvars_in:
                    continue

                # Only continue if the input exists on this processor
                if abs_in in abs2meta['input']:

                    indices = None
                    # Get meta
                    meta_in = abs2meta['input'][abs_in]
                    meta_out = allprocs_abs2meta_out[abs_out]

                    idx_in = allprocs_abs2idx[abs_in]
                    idx_out = allprocs_abs2idx[abs_out]

                    # Read in and process src_indices
                    src_indices = meta_in['src_indices']
                    if src_indices is not None:
                        if src_indices.ndim == 1:
                            src_indices = convert_neg(src_indices, meta_out['global_size'])

                    # 1. Compute the output indices
                    offset = offsets_out[iproc, idx_out]
                    if src_indices is None:
                        output_inds = np.arange(offset, offset + meta_in['size'], dtype=INT_DTYPE)
                    else:
                        output_inds = src_indices + offset

                    # 2. Compute the input indices
                    input_inds = np.arange(offsets_in[iproc, idx_in],
                                           offsets_in[iproc, idx_in] +
                                           sizes_in[iproc, idx_in], dtype=INT_DTYPE)
                    if indices is not None:
                        input_inds = input_inds.reshape(indices.shape)

                    # Now the indices are ready - input_inds, output_inds
                    sub_in = abs_in[mypathlen:].split('.', 1)[0]
                    fwd_xfer_in[sub_in].append(input_inds)
                    fwd_xfer_out[sub_in].append(output_inds)
                    if rev and abs_out in abs2meta['output']:
                        sub_out = abs_out[mypathlen:].split('.', 1)[0]
                        rev_xfer_in[sub_out].append(input_inds)
                        rev_xfer_out[sub_out].append(output_inds)

            tot_size = 0
            for sname, inds in fwd_xfer_in.items():
                fwd_xfer_in[sname] = arr = _merge(inds)
                fwd_xfer_out[sname] = _merge(fwd_xfer_out[sname])
                tot_size += arr.size

            if rev:
                for sname, inds in rev_xfer_in.items():
                    rev_xfer_in[sname] = _merge(inds)
                    rev_xfer_out[sname] = _merge(rev_xfer_out[sname])

            transfers[vec_name] = {}

            if tot_size > 0:
                try:
                    xfer_in = np.concatenate(list(fwd_xfer_in.values()))
                    xfer_out = np.concatenate(list(fwd_xfer_out.values()))
                except ValueError:
                    xfer_in = xfer_out = np.zeros(0, dtype=INT_DTYPE)

                out_vec = vectors['output'][vec_name]

                xfer_all = DefaultTransfer(vectors['input'][vec_name], out_vec,
                                           xfer_in, xfer_out, group.comm)
            else:
                xfer_all = None

            transfers[vec_name]['fwd'] = xfwd = {}
            xfwd[None] = xfer_all
            if rev:
                transfers[vec_name]['rev'] = xrev = {}
                xrev[None] = xfer_all

            for sname, inds in fwd_xfer_in.items():
                if inds.size > 0:
                    xfwd[sname] = DefaultTransfer(vectors['input'][vec_name],
                                                  vectors['output'][vec_name],
                                                  inds, fwd_xfer_out[sname], group.comm)
                else:
                    xfwd[sname] = None

            if rev:
                for sname, inds in rev_xfer_out.items():
                    if inds.size > 0:
                        xrev[sname] = DefaultTransfer(vectors['input'][vec_name],
                                                      vectors['output'][vec_name],
                                                      rev_xfer_in[sname], inds, group.comm)
                    else:
                        xrev[sname] = None

        if group._use_derivatives:
            transfers['nonlinear'] = transfers['linear']
示例#4
0
    def _setup_transfers(group, recurse=True):
        """
        Compute all transfers that are owned by our parent group.

        Parameters
        ----------
        group : <Group>
            Parent group.
        recurse : bool
            Whether to call this method in subsystems.
        """
        iproc = group.comm.rank
        rev = group._mode == 'rev' or group._mode == 'auto'

        if recurse:
            for subsys in group._subgroups_myproc:
                subsys._setup_transfers(recurse)

        abs2meta = group._var_abs2meta
        allprocs_abs2meta = group._var_allprocs_abs2meta

        group._transfers = transfers = {}
        vectors = group._vectors
        offsets = _global2local_offsets(group._get_var_offsets())

        vec_names = group._lin_rel_vec_name_list if group._use_derivatives else group._vec_names

        mypathlen = len(group.pathname + '.' if group.pathname else '')
        sub_inds = group._subsystems_inds

        for vec_name in vec_names:
            relvars, _ = group._relevant[vec_name]['@all']
            relvars_in = relvars['input']
            relvars_out = relvars['output']

            # Initialize empty lists for the transfer indices
            nsub_allprocs = len(group._subsystems_allprocs)
            xfer_in = []
            xfer_out = []
            fwd_xfer_in = [[] for s in group._subsystems_allprocs]
            fwd_xfer_out = [[] for s in group._subsystems_allprocs]
            if rev:
                rev_xfer_in = [[] for s in group._subsystems_allprocs]
                rev_xfer_out = [[] for s in group._subsystems_allprocs]

            allprocs_abs2idx = group._var_allprocs_abs2idx[vec_name]
            sizes_in = group._var_sizes[vec_name]['input']
            sizes_out = group._var_sizes[vec_name]['output']
            offsets_in = offsets[vec_name]['input']
            offsets_out = offsets[vec_name]['output']

            # Loop through all connections owned by this group
            for abs_in, abs_out in group._conn_abs_in2out.items():
                if abs_out not in relvars_out or abs_in not in relvars_in:
                    continue

                # Only continue if the input exists on this processor
                if abs_in in abs2meta:

                    # Get meta
                    meta_in = abs2meta[abs_in]
                    meta_out = allprocs_abs2meta[abs_out]

                    idx_in = allprocs_abs2idx[abs_in]
                    idx_out = allprocs_abs2idx[abs_out]

                    # Read in and process src_indices
                    src_indices = meta_in['src_indices']
                    if src_indices is None:
                        pass
                    elif src_indices.ndim == 1:
                        src_indices = convert_neg(src_indices,
                                                  meta_out['global_size'])
                    else:
                        src_indices = _flatten_src_indices(
                            src_indices, meta_in['shape'],
                            meta_out['global_shape'], meta_out['global_size'])

                    # 1. Compute the output indices
                    offset = offsets_out[iproc, idx_out]
                    if src_indices is None:
                        output_inds = np.arange(offset,
                                                offset + meta_in['size'],
                                                dtype=INT_DTYPE)
                    else:
                        output_inds = src_indices + offset

                    # 2. Compute the input indices
                    input_inds = np.arange(offsets_in[iproc, idx_in],
                                           offsets_in[iproc, idx_in] +
                                           sizes_in[iproc, idx_in],
                                           dtype=INT_DTYPE)

                    # Now the indices are ready - input_inds, output_inds
                    sub_in = abs_in[mypathlen:].split('.', 1)[0]
                    isub = sub_inds[sub_in]
                    fwd_xfer_in[isub].append(input_inds)
                    fwd_xfer_out[isub].append(output_inds)
                    if rev and abs_out in abs2meta:
                        sub_out = abs_out[mypathlen:].split('.', 1)[0]
                        isub = sub_inds[sub_out]
                        rev_xfer_in[isub].append(input_inds)
                        rev_xfer_out[isub].append(output_inds)

            tot_size = 0
            for isub in range(nsub_allprocs):
                fwd_xfer_in[isub] = _merge(fwd_xfer_in[isub])
                fwd_xfer_out[isub] = _merge(fwd_xfer_out[isub])
                tot_size += fwd_xfer_in[isub].size
                if rev:
                    rev_xfer_in[isub] = _merge(rev_xfer_in[isub])
                    rev_xfer_out[isub] = _merge(rev_xfer_out[isub])

            transfers[vec_name] = {}

            if tot_size > 0:
                xfer_in = np.concatenate(fwd_xfer_in)
                xfer_out = np.concatenate(fwd_xfer_out)

                out_vec = vectors['output'][vec_name]

                xfer_all = DefaultTransfer(vectors['input'][vec_name], out_vec,
                                           xfer_in, xfer_out, group.comm)
            else:
                xfer_all = None
            transfers[vec_name]['fwd', None] = xfer_all
            if rev:
                transfers[vec_name]['rev', None] = xfer_all
            for isub in range(nsub_allprocs):
                if fwd_xfer_in[isub].size > 0:
                    transfers[vec_name]['fwd', isub] = DefaultTransfer(
                        vectors['input'][vec_name],
                        vectors['output'][vec_name], fwd_xfer_in[isub],
                        fwd_xfer_out[isub], group.comm)
                else:
                    transfers[vec_name]['fwd', isub] = None
                if rev:
                    if rev_xfer_out[isub].size > 0:
                        transfers[vec_name]['rev', isub] = DefaultTransfer(
                            vectors['input'][vec_name],
                            vectors['output'][vec_name], rev_xfer_in[isub],
                            rev_xfer_out[isub], group.comm)
                    else:
                        transfers[vec_name]['rev', isub] = None

        if group._use_derivatives:
            transfers['nonlinear'] = transfers['linear']
示例#5
0
    def _setup_transfers(group):
        """
        Compute all transfers that are owned by our parent group.

        Parameters
        ----------
        group : <Group>
            Parent group.
        """
        iproc = group.comm.rank
        rev = group._mode == 'rev' or group._mode == 'auto'

        for subsys in group._subgroups_myproc:
            subsys._setup_transfers()

        abs2meta = group._var_abs2meta

        group._transfers = transfers = {}
        vectors = group._vectors
        offsets = _global2local_offsets(group._get_var_offsets())
        mypathlen = len(group.pathname + '.' if group.pathname else '')

        # Initialize empty lists for the transfer indices
        xfer_in = []
        xfer_out = []
        fwd_xfer_in = defaultdict(list)
        fwd_xfer_out = defaultdict(list)
        if rev:
            rev_xfer_in = defaultdict(list)
            rev_xfer_out = defaultdict(list)

        allprocs_abs2idx = group._var_allprocs_abs2idx
        sizes_in = group._var_sizes['input']
        offsets_in = offsets['input']
        if sizes_in.size > 0:
            sizes_in = sizes_in[iproc]
            offsets_in = offsets_in[iproc]
        offsets_out = offsets['output']
        if offsets_out.size > 0:
            offsets_out = offsets_out[iproc]

        # Loop through all connections owned by this group
        for abs_in, abs_out in group._conn_abs_in2out.items():
            # This weeds out discrete vars (all vars are local if using this Transfer)
            if abs_in in abs2meta['input']:

                indices = None
                # Get meta
                meta_in = abs2meta['input'][abs_in]

                idx_in = allprocs_abs2idx[abs_in]
                idx_out = allprocs_abs2idx[abs_out]

                # Read in and process src_indices
                src_indices = meta_in['src_indices']
                if src_indices is not None:
                    src_indices = src_indices.shaped_array()

                # 1. Compute the output indices
                offset = offsets_out[idx_out]
                if src_indices is None:
                    output_inds = np.arange(offset, offset + meta_in['size'], dtype=INT_DTYPE)
                else:
                    output_inds = src_indices + offset

                # 2. Compute the input indices
                input_inds = np.arange(offsets_in[idx_in],
                                       offsets_in[idx_in] + sizes_in[idx_in], dtype=INT_DTYPE)
                if indices is not None:
                    input_inds = input_inds.reshape(indices.shape)

                # Now the indices are ready - input_inds, output_inds
                sub_in = abs_in[mypathlen:].split('.', 1)[0]
                fwd_xfer_in[sub_in].append(input_inds)
                fwd_xfer_out[sub_in].append(output_inds)
                if rev and abs_out in abs2meta['output']:
                    sub_out = abs_out[mypathlen:].split('.', 1)[0]
                    rev_xfer_in[sub_out].append(input_inds)
                    rev_xfer_out[sub_out].append(output_inds)

        tot_size = 0
        for sname, inds in fwd_xfer_in.items():
            fwd_xfer_in[sname] = arr = _merge(inds)
            fwd_xfer_out[sname] = _merge(fwd_xfer_out[sname])
            tot_size += arr.size

        if rev:
            for sname, inds in rev_xfer_in.items():
                rev_xfer_in[sname] = _merge(inds)
                rev_xfer_out[sname] = _merge(rev_xfer_out[sname])

        if tot_size > 0:
            try:
                xfer_in = np.concatenate(list(fwd_xfer_in.values()))
                xfer_out = np.concatenate(list(fwd_xfer_out.values()))
            except ValueError:
                xfer_in = xfer_out = np.zeros(0, dtype=INT_DTYPE)

            xfer_all = DefaultTransfer(vectors['input']['nonlinear'],
                                       vectors['output']['nonlinear'], xfer_in, xfer_out,
                                       group.comm)
        else:
            xfer_all = None

        transfers['fwd'] = xfwd = {}
        xfwd[None] = xfer_all
        if rev:
            transfers['rev'] = xrev = {}
            xrev[None] = xfer_all

        for sname, inds in fwd_xfer_in.items():
            if inds.size > 0:
                xfwd[sname] = DefaultTransfer(vectors['input']['nonlinear'],
                                              vectors['output']['nonlinear'],
                                              inds, fwd_xfer_out[sname], group.comm)
            else:
                xfwd[sname] = None

        if rev:
            for sname, inds in rev_xfer_out.items():
                if inds.size > 0:
                    xrev[sname] = DefaultTransfer(vectors['input']['nonlinear'],
                                                  vectors['output']['nonlinear'],
                                                  rev_xfer_in[sname], inds, group.comm)
                else:
                    xrev[sname] = None