from __future__ import annotations import itertools import os from collections.abc import Hashable, Iterable, Mapping, Sequence from itertools import product from math import prod from typing import Any import tlz as toolz import dask from dask.base import clone_key, get_name_from_key, tokenize from dask.core import flatten, ishashable, keys_in_tasks, reverse_dict from dask.highlevelgraph import HighLevelGraph, Layer from dask.optimization import SubgraphCallable, fuse from dask.typing import Graph, Key from dask.utils import ( _deprecated, apply, ensure_dict, homogeneous_deepmap, stringify_collection_keys, ) class BlockwiseDep: """Blockwise-IO argument This is the base class for indexable Blockwise-IO arguments. When constructing a ``Blockwise`` Layer, one or more of the collection tuples passed in with ``indices`` may contain a ``BlockwiseDep`` instance (in place of a "real" collection name). This allows a new collection to be created (via IO) within a ``Blockwise`` layer. Parameters ---------- numblocks: tuple[int, ...] The number of blocks/partitions the object can support along each dimension. produces_tasks: bool Whether any nested tasks will be passed to the Blockwise function. See Also -------- dask.blockwise.Blockwise dask.blockwise.BlockwiseDepDict """ numblocks: tuple[int, ...] produces_tasks: bool def __getitem__(self, idx: tuple[int, ...]) -> Any: """Return Blockwise-function arguments for a specific index""" raise NotImplementedError( "Must define `__getitem__` for `BlockwiseDep` subclass." ) def get(self, idx: tuple[int, ...], default) -> Any: """BlockwiseDep ``__getitem__`` Wrapper""" try: return self.__getitem__(idx) except KeyError: return default @property def produces_keys(self) -> bool: """Whether this object will produce external key dependencies. An external key corresponds to a task key or ``Delayed``-object key that does not originate from within the ``Blockwise`` layer that is including this ``BlockwiseDep`` object in its ``indices``. A ``BlockwiseDep`` object should only return external-key dependencies when those dependencies do not correspond to a blockwise-compatible Dask collection (otherwise the collection name should just be included in ``indices`` list instead). """ return False def __repr__(self) -> str: return f"<{type(self).__name__} {self.numblocks}>" class BlockwiseDepDict(BlockwiseDep): """Dictionary-based Blockwise-IO argument This is a dictionary-backed instance of ``BlockwiseDep``. The purpose of this class is to simplify the construction of IO-based Blockwise Layers with block/partition-dependent function arguments that are difficult to calculate at graph-materialization time. Examples -------- Specify an IO-based function for the Blockwise Layer. Note that the function will be passed a single input object when the task is executed (e.g. a single ``tuple`` or ``dict``): >>> import pandas as pd >>> func = lambda x: pd.read_csv(**x) Use ``BlockwiseDepDict`` to define the input argument to ``func`` for each block/partition: >>> dep = BlockwiseDepDict( ... mapping={ ... (0,) : { ... "filepath_or_buffer": "data.csv", ... "skiprows": 1, ... "nrows": 2, ... "names": ["a", "b"], ... }, ... (1,) : { ... "filepath_or_buffer": "data.csv", ... "skiprows": 3, ... "nrows": 2, ... "names": ["a", "b"], ... }, ... } ... ) Construct a Blockwise Layer with ``dep`` specified in the ``indices`` list: >>> layer = Blockwise( ... output="collection-name", ... output_indices="i", ... dsk={"collection-name": (func, '_0')}, ... indices=[(dep, "i")], ... numblocks={}, ... ) See Also -------- dask.blockwise.Blockwise dask.blockwise.BlockwiseDep """ def __init__( self, mapping: dict, numblocks: tuple[int, ...] | None = None, produces_tasks: bool = False, produces_keys: bool = False, ): self.mapping = mapping self.produces_tasks = produces_tasks # By default, assume 1D shape self.numblocks = numblocks or (len(mapping),) # Whether `mapping` values are real task keys # (e.g. Delayed objects) self._produces_keys = produces_keys @property def produces_keys(self) -> bool: return self._produces_keys def __getitem__(self, idx: tuple[int, ...]) -> Any: try: return self.mapping[idx] except KeyError as err: # If a DataFrame collection was converted # to an Array collection, the dimension of # `idx` may not agree with the keys in # `self.mapping`. In this case, we can # use `self.numblocks` to check for a key # match in the leading elements of `idx` flat_idx = idx[: len(self.numblocks)] if flat_idx in self.mapping: return self.mapping[flat_idx] raise err def __len__(self) -> int: return len(self.mapping) class BlockIndex(BlockwiseDep): """Index BlockwiseDep argument The purpose of this class is to provide each block of a ``Blockwise``-based operation with the current block index. """ produces_tasks: bool = False def __init__(self, numblocks: tuple[int, ...]): # NOTE: Unused - Just needs to be set to # follow the `BlockwiseDep` interface self.numblocks = numblocks def __getitem__(self, idx: tuple[int, ...]) -> tuple[int, ...]: return idx def subs(task, substitution): """Create a new task with the values substituted This is like dask.core.subs, but takes a dict of many substitutions to perform simultaneously. It is not as concerned with micro performance. """ if isinstance(task, dict): return {k: subs(v, substitution) for k, v in task.items()} if type(task) in (tuple, list, set): return type(task)([subs(x, substitution) for x in task]) try: return substitution[task] except (KeyError, TypeError): return task def index_subs(ind, substitution): """A simple subs function that works both on tuples and strings""" if ind is None: return ind else: return tuple(substitution.get(c, c) for c in ind) _BLOCKWISE_DEFAULT_PREFIX = "__dask_blockwise__" def blockwise_token(i, prefix=_BLOCKWISE_DEFAULT_PREFIX): return prefix + "%d" % i def blockwise( func, output, output_indices, *arrind_pairs, numblocks=None, concatenate=None, new_axes=None, dependencies=(), **kwargs, ): """Create a Blockwise symbolic mutable mapping This is like the ``make_blockwise_graph`` function, but rather than construct a dict, it returns a symbolic Blockwise object. ``*arrind_pairs`` is similar to those in `make_blockwise_graph`, but in addition to allowing for collections it can accept BlockwiseDep instances, which allows for lazy evaluation of arguments to ``func`` which might be different for different chunks/partitions. See Also -------- make_blockwise_graph Blockwise """ new_axes = new_axes or {} arrind_pairs = list(arrind_pairs) # Transform indices to canonical elements # We use terms like _0, and _1 rather than provided index elements unique_indices = { i for ii in arrind_pairs[1::2] if ii is not None for i in ii } | set(output_indices) sub = {k: blockwise_token(i, ".") for i, k in enumerate(sorted(unique_indices))} output_indices = index_subs(tuple(output_indices), sub) a_pairs_list = [] for a in arrind_pairs[1::2]: if a is not None: val = tuple(a) else: val = a a_pairs_list.append(index_subs(val, sub)) arrind_pairs[1::2] = a_pairs_list new_axes = {index_subs((k,), sub)[0]: v for k, v in new_axes.items()} # Unpack dask values in non-array arguments inputs = [] inputs_indices = [] for name, index in toolz.partition(2, arrind_pairs): inputs.append(name) inputs_indices.append(index) # Unpack delayed objects in kwargs new_keys = {n for c in dependencies for n in c.__dask_layers__()} if kwargs: # replace keys in kwargs with _0 tokens new_tokens = tuple( blockwise_token(i) for i in range(len(inputs), len(inputs) + len(new_keys)) ) sub = dict(zip(new_keys, new_tokens)) inputs.extend(new_keys) inputs_indices.extend((None,) * len(new_keys)) kwargs = subs(kwargs, sub) indices = [(k, v) for k, v in zip(inputs, inputs_indices)] keys = map(blockwise_token, range(len(inputs))) # Construct local graph if not kwargs: subgraph = {output: (func,) + tuple(keys)} else: _keys = list(keys) if new_keys: _keys = _keys[: -len(new_keys)] kwargs2 = (dict, list(map(list, kwargs.items()))) subgraph = {output: (apply, func, _keys, kwargs2)} # Construct final output subgraph = Blockwise( output, output_indices, subgraph, indices, numblocks=numblocks, concatenate=concatenate, new_axes=new_axes, ) return subgraph class Blockwise(Layer): """Tensor Operation This is a lazily constructed mapping for tensor operation graphs. This defines a dictionary using an operation and an indexing pattern. It is built for many operations like elementwise, transpose, tensordot, and so on. We choose to keep these as symbolic mappings rather than raw dictionaries because we are able to fuse them during optimization, sometimes resulting in much lower overhead. Parameters ---------- output: str The name of the output collection. Used in keynames output_indices: tuple The output indices, like ``('i', 'j', 'k')`` used to determine the structure of the block computations dsk: dict A small graph to apply per-output-block. May include keys from the input indices. indices: tuple[tuple[str, tuple[str, ...] | None], ...] An ordered mapping from input key name, like ``'x'`` to input indices, like ``('i', 'j')`` Or includes literals, which have ``None`` for an index value. In place of input-key names, the first tuple element may also be a ``BlockwiseDep`` object. numblocks: Mapping[key, Sequence[int]] Number of blocks along each dimension for each input concatenate: bool Whether or not to pass contracted dimensions as a list of inputs or a single input to the block function new_axes: Mapping New index dimensions that may have been created and their size, e.g. ``{'j': 2, 'k': 3}`` output_blocks: set[tuple[int, ...]] Specify a specific set of required output blocks. Since the graph will only contain the necessary tasks to generate these outputs, this kwarg can be used to "cull" the abstract layer (without needing to materialize the low-level graph). annotations: dict (optional) Layer annotations io_deps: dict[str, BlockwiseDep] (optional) Dictionary containing the mapping between "place-holder" collection keys and ``BlockwiseDep``-based objects. **WARNING**: This argument should only be used internally (for culling, fusion and cloning of existing Blockwise layers). Explicit use of this argument will be deprecated in the future. See Also -------- dask.blockwise.blockwise dask.array.blockwise """ output: str output_indices: tuple[str, ...] dsk: Graph indices: tuple[tuple[str, tuple[str, ...] | None], ...] numblocks: Mapping[str, Sequence[int]] concatenate: bool | None new_axes: Mapping[str, int] output_blocks: set[tuple[int, ...]] | None io_deps: Mapping[str, BlockwiseDep] def __init__( self, output: str, output_indices: Iterable[str], dsk: Graph, indices: Iterable[tuple[str | BlockwiseDep, Iterable[str] | None]], numblocks: Mapping[str, Sequence[int]], concatenate: bool | None = None, new_axes: Mapping[str, int] | None = None, output_blocks: set[tuple[int, ...]] | None = None, annotations: Mapping[str, Any] | None = None, io_deps: Mapping[str, BlockwiseDep] | None = None, ): super().__init__(annotations=annotations) self.output = output self.output_indices = tuple(output_indices) self.output_blocks = output_blocks self.dsk = dsk # Remove `BlockwiseDep` arguments from input indices # and add them to `self.io_deps`. # TODO: Remove `io_deps` and handle indexable objects # in `self.indices` throughout `Blockwise`. _tmp_indices = [] if indices: numblocks = ensure_dict(numblocks, copy=True) io_deps = ensure_dict(io_deps or {}, copy=True) for dep, ind in indices: if isinstance(dep, BlockwiseDep): name = tokenize(dep) io_deps[name] = dep numblocks[name] = dep.numblocks else: name = dep _tmp_indices.append((name, tuple(ind) if ind is not None else ind)) self.numblocks = numblocks self.io_deps = io_deps or {} self.indices = tuple(_tmp_indices) # optimize_blockwise won't merge where `concatenate` doesn't match, so # enforce a canonical value if there are no axes for reduction. output_indices_set = set(self.output_indices) if concatenate is not None and all( i in output_indices_set for name, ind in self.indices if ind is not None for i in ind ): concatenate = None self.concatenate = concatenate self.new_axes = new_axes or {} @property def dims(self): """Returns a dictionary mapping between each index specified in `self.indices` and the number of output blocks for that indice. """ if not hasattr(self, "_dims"): self._dims = _make_dims(self.indices, self.numblocks, self.new_axes) return self._dims def __repr__(self): return f"Blockwise<{self.indices} -> {self.output}>" @property def _dict(self): if hasattr(self, "_cached_dict"): return self._cached_dict["dsk"] else: keys = tuple(map(blockwise_token, range(len(self.indices)))) dsk, _ = fuse(self.dsk, [self.output]) func = SubgraphCallable(dsk, self.output, keys) dsk = make_blockwise_graph( func, self.output, self.output_indices, *list(toolz.concat(self.indices)), new_axes=self.new_axes, numblocks=self.numblocks, concatenate=self.concatenate, output_blocks=self.output_blocks, dims=self.dims, io_deps=self.io_deps, ) self._cached_dict = {"dsk": dsk} return self._cached_dict["dsk"] def get_output_keys(self): if self.output_blocks: # Culling has already generated a list of output blocks return {(self.output, *p) for p in self.output_blocks} # Return all possible output keys (no culling) return { (self.output, *p) for p in itertools.product( *[range(self.dims[i]) for i in self.output_indices] ) } def __getitem__(self, key): return self._dict[key] def __iter__(self): return iter(self._dict) def __len__(self) -> int: # same method as `get_output_keys`, without manifesting the keys themselves return ( len(self.output_blocks) if self.output_blocks else prod(self.dims[i] for i in self.output_indices) ) def is_materialized(self): return hasattr(self, "_cached_dict") def _cull_dependencies(self, all_hlg_keys, output_blocks): """Determine the necessary dependencies to produce `output_blocks`. This method does not require graph materialization. """ # Check `concatenate` option concatenate = None if self.concatenate is True: from dask.array.core import concatenate_axes as concatenate # Generate coordinate map (coord_maps, concat_axes, dummies) = _get_coord_mapping( self.dims, self.output, self.output_indices, self.numblocks, self.indices, concatenate, ) # Gather constant dependencies (for all output keys) const_deps = set() for arg, ind in self.indices: if ind is None: try: if arg in all_hlg_keys: const_deps.add(arg) except TypeError: pass # unhashable # Get dependencies for each output block key_deps = {} for out_coords in output_blocks: deps = set() coords = out_coords + dummies for cmap, axes, (arg, ind) in zip(coord_maps, concat_axes, self.indices): if ind is not None and arg not in self.io_deps: arg_coords = tuple(coords[c] for c in cmap) if axes: tups = lol_product((arg,), arg_coords) deps.update(flatten(tups)) if concatenate: tups = (concatenate, tups, axes) else: tups = (arg,) + arg_coords deps.add(tups) key_deps[(self.output,) + out_coords] = deps | const_deps # Add valid-key dependencies from io_deps for key, io_dep in self.io_deps.items(): if io_dep.produces_keys: for out_coords in output_blocks: key = (self.output,) + out_coords valid_key_dep = io_dep[out_coords] key_deps[key] |= {valid_key_dep} return key_deps def _cull(self, output_blocks): return Blockwise( self.output, self.output_indices, self.dsk, self.indices, self.numblocks, concatenate=self.concatenate, new_axes=self.new_axes, output_blocks=output_blocks, annotations=self.annotations, io_deps=self.io_deps, ) def cull( self, keys: set, all_hlg_keys: Iterable ) -> tuple[Layer, Mapping[Key, set[Key]]]: # Culling is simple for Blockwise layers. We can just # collect a set of required output blocks (tuples), and # only construct graph for these blocks in `make_blockwise_graph` output_blocks: set[tuple[int, ...]] = set() for key in keys: if key[0] == self.output: output_blocks.add(key[1:]) culled_deps = self._cull_dependencies(all_hlg_keys, output_blocks) out_size_iter = (self.dims[i] for i in self.output_indices) if prod(out_size_iter) != len(culled_deps): culled_layer = self._cull(output_blocks) return culled_layer, culled_deps else: return self, culled_deps def clone( self, keys: set[Key], seed: Hashable, bind_to: Key | None = None, ) -> tuple[Layer, bool]: names = {get_name_from_key(k) for k in keys} # We assume that 'keys' will contain either all or none of the output keys of # each of the layers, because clone/bind are always invoked at collection level. # Asserting this is very expensive, so we only check it during unit tests. if "PYTEST_CURRENT_TEST" in os.environ: assert not self.get_output_keys() - keys for name, nb in self.numblocks.items(): if name in names: for block in product(*(list(range(nbi)) for nbi in nb)): assert (name, *block) in keys is_leaf = True indices = [] k: Key for k, idxv in self.indices: # Note: k may not be a key and thus not be hashable in the case where # one or more args of blockwise() are sequences of literals; # e.g. k = (list, [0, 1, 2]) # See https://github.com/dask/dask/issues/8978 if ishashable(k) and k in names: is_leaf = False k = clone_key(k, seed) indices.append((k, idxv)) numblocks: dict[str, Sequence[int]] = {} for k, nbv in self.numblocks.items(): if k in names: is_leaf = False k = clone_key(k, seed) numblocks[k] = nbv dsk = {clone_key(k, seed): v for k, v in self.dsk.items()} if bind_to is not None and is_leaf: from dask.graph_manipulation import chunks # It's always a Delayed generated by dask.graph_manipulation.checkpoint; # the layer name always matches the key assert isinstance(bind_to, str) dsk = {k: (chunks.bind, v, f"_{len(indices)}") for k, v in dsk.items()} indices.append((bind_to, None)) return ( Blockwise( output=clone_key(self.output, seed), output_indices=self.output_indices, dsk=dsk, indices=indices, numblocks=numblocks, concatenate=self.concatenate, new_axes=self.new_axes, output_blocks=self.output_blocks, annotations=self.annotations, io_deps=self.io_deps, ), (bind_to is not None and is_leaf), ) def _get_coord_mapping( dims, output, out_indices, numblocks, argpairs, concatenate, ): """Calculate coordinate mapping for graph construction. This function handles the high-level logic behind Blockwise graph construction. The output is a tuple containing: The mapping between input and output block coordinates (`coord_maps`), the axes along which to concatenate for each input (`concat_axes`), and the dummy indices needed for broadcasting (`dummies`). Used by `make_blockwise_graph` and `Blockwise._cull_dependencies`. Parameters ---------- dims : dict Mapping between each index specified in `argpairs` and the number of output blocks for that index. Corresponds to the Blockwise `dims` attribute. output : str Corresponds to the Blockwise `output` attribute. out_indices : tuple Corresponds to the Blockwise `output_indices` attribute. numblocks : dict Corresponds to the Blockwise `numblocks` attribute. argpairs : tuple Corresponds to the Blockwise `indices` attribute. concatenate : bool Corresponds to the Blockwise `concatenate` attribute. """ block_names = set() all_indices = set() for name, ind in argpairs: if ind is not None: block_names.add(name) for x in ind: all_indices.add(x) assert set(numblocks) == block_names dummy_indices = all_indices - set(out_indices) # For each position in the output space, we'll construct a # "coordinate set" that consists of # - the output indices # - the dummy indices # - the dummy indices, with indices replaced by zeros (for broadcasting), we # are careful to only emit a single dummy zero when concatenate=True to not # concatenate the same array with itself several times. # - a 0 to assist with broadcasting. index_pos, zero_pos = {}, {} for i, ind in enumerate(out_indices): index_pos[ind] = i zero_pos[ind] = -1 _dummies_list = [] for i, ind in enumerate(dummy_indices): index_pos[ind] = 2 * i + len(out_indices) zero_pos[ind] = 2 * i + 1 + len(out_indices) reps = 1 if concatenate else dims[ind] _dummies_list.append([list(range(dims[ind])), [0] * reps]) # ([0, 1, 2], [0, 0, 0], ...) For a dummy index of dimension 3 dummies = tuple(itertools.chain.from_iterable(_dummies_list)) dummies += (0,) # For each coordinate position in each input, gives the position in # the coordinate set. coord_maps = [] # Axes along which to concatenate, for each input concat_axes = [] for arg, ind in argpairs: if ind is not None: coord_maps.append( [ zero_pos[i] if nb == 1 else index_pos[i] for i, nb in zip(ind, numblocks[arg]) ] ) concat_axes.append([n for n, i in enumerate(ind) if i in dummy_indices]) else: coord_maps.append(None) concat_axes.append(None) return coord_maps, concat_axes, dummies def make_blockwise_graph( func, output, out_indices, *arrind_pairs, numblocks=None, concatenate=None, new_axes=None, output_blocks=None, dims=None, deserializing=False, func_future_args=None, return_key_deps=False, io_deps=None, ): """Tensor operation Applies a function, ``func``, across blocks from many different input collections. We arrange the pattern with which those blocks interact with sets of matching indices. E.g.:: make_blockwise_graph(func, 'z', 'i', 'x', 'i', 'y', 'i') yield an embarrassingly parallel communication pattern and is read as $$ z_i = func(x_i, y_i) $$ More complex patterns may emerge, including multiple indices:: make_blockwise_graph(func, 'z', 'ij', 'x', 'ij', 'y', 'ji') $$ z_{ij} = func(x_{ij}, y_{ji}) $$ Indices missing in the output but present in the inputs results in many inputs being sent to one function (see examples). Examples -------- Simple embarrassing map operation >>> inc = lambda x: x + 1 >>> make_blockwise_graph(inc, 'z', 'ij', 'x', 'ij', numblocks={'x': (2, 2)}) # doctest: +SKIP {('z', 0, 0): (inc, ('x', 0, 0)), ('z', 0, 1): (inc, ('x', 0, 1)), ('z', 1, 0): (inc, ('x', 1, 0)), ('z', 1, 1): (inc, ('x', 1, 1))} Simple operation on two datasets >>> add = lambda x, y: x + y >>> make_blockwise_graph(add, 'z', 'ij', 'x', 'ij', 'y', 'ij', numblocks={'x': (2, 2), ... 'y': (2, 2)}) # doctest: +SKIP {('z', 0, 0): (add, ('x', 0, 0), ('y', 0, 0)), ('z', 0, 1): (add, ('x', 0, 1), ('y', 0, 1)), ('z', 1, 0): (add, ('x', 1, 0), ('y', 1, 0)), ('z', 1, 1): (add, ('x', 1, 1), ('y', 1, 1))} Operation that flips one of the datasets >>> addT = lambda x, y: x + y.T # Transpose each chunk >>> # z_ij ~ x_ij y_ji >>> # .. .. .. notice swap >>> make_blockwise_graph(addT, 'z', 'ij', 'x', 'ij', 'y', 'ji', numblocks={'x': (2, 2), ... 'y': (2, 2)}) # doctest: +SKIP {('z', 0, 0): (add, ('x', 0, 0), ('y', 0, 0)), ('z', 0, 1): (add, ('x', 0, 1), ('y', 1, 0)), ('z', 1, 0): (add, ('x', 1, 0), ('y', 0, 1)), ('z', 1, 1): (add, ('x', 1, 1), ('y', 1, 1))} Dot product with contraction over ``j`` index. Yields list arguments >>> make_blockwise_graph(dotmany, 'z', 'ik', 'x', 'ij', 'y', 'jk', numblocks={'x': (2, 2), ... 'y': (2, 2)}) # doctest: +SKIP {('z', 0, 0): (dotmany, [('x', 0, 0), ('x', 0, 1)], [('y', 0, 0), ('y', 1, 0)]), ('z', 0, 1): (dotmany, [('x', 0, 0), ('x', 0, 1)], [('y', 0, 1), ('y', 1, 1)]), ('z', 1, 0): (dotmany, [('x', 1, 0), ('x', 1, 1)], [('y', 0, 0), ('y', 1, 0)]), ('z', 1, 1): (dotmany, [('x', 1, 0), ('x', 1, 1)], [('y', 0, 1), ('y', 1, 1)])} Pass ``concatenate=True`` to concatenate arrays ahead of time >>> make_blockwise_graph(f, 'z', 'i', 'x', 'ij', 'y', 'ij', concatenate=True, ... numblocks={'x': (2, 2), 'y': (2, 2,)}) # doctest: +SKIP {('z', 0): (f, (concatenate_axes, [('x', 0, 0), ('x', 0, 1)], (1,)), (concatenate_axes, [('y', 0, 0), ('y', 0, 1)], (1,))) ('z', 1): (f, (concatenate_axes, [('x', 1, 0), ('x', 1, 1)], (1,)), (concatenate_axes, [('y', 1, 0), ('y', 1, 1)], (1,)))} Supports Broadcasting rules >>> make_blockwise_graph(add, 'z', 'ij', 'x', 'ij', 'y', 'ij', numblocks={'x': (1, 2), ... 'y': (2, 2)}) # doctest: +SKIP {('z', 0, 0): (add, ('x', 0, 0), ('y', 0, 0)), ('z', 0, 1): (add, ('x', 0, 1), ('y', 0, 1)), ('z', 1, 0): (add, ('x', 0, 0), ('y', 1, 0)), ('z', 1, 1): (add, ('x', 0, 1), ('y', 1, 1))} Support keyword arguments with apply >>> def f(a, b=0): return a + b >>> make_blockwise_graph(f, 'z', 'i', 'x', 'i', numblocks={'x': (2,)}, b=10) # doctest: +SKIP {('z', 0): (apply, f, [('x', 0)], {'b': 10}), ('z', 1): (apply, f, [('x', 1)], {'b': 10})} Include literals by indexing with ``None`` >>> make_blockwise_graph(add, 'z', 'i', 'x', 'i', 100, None, numblocks={'x': (2,)}) # doctest: +SKIP {('z', 0): (add, ('x', 0), 100), ('z', 1): (add, ('x', 1), 100)} See Also -------- dask.array.blockwise dask.blockwise.blockwise """ if numblocks is None: raise ValueError("Missing required numblocks argument.") new_axes = new_axes or {} io_deps = io_deps or {} argpairs = list(toolz.partition(2, arrind_pairs)) if return_key_deps: key_deps = {} if deserializing: from distributed.protocol.serialize import to_serialize if concatenate is True: from dask.array.core import concatenate_axes as concatenate # Dictionary mapping {i: 3, j: 4, ...} for i, j, ... the dimensions dims = dims or _make_dims(argpairs, numblocks, new_axes) # Generate the abstract "plan" before constructing # the actual graph (coord_maps, concat_axes, dummies) = _get_coord_mapping( dims, output, out_indices, numblocks, argpairs, concatenate, ) # Apply Culling. # Only need to construct the specified set of output blocks. # Note that we must convert itertools.product to list, # because we may need to loop through output_blocks more than # once below (itertools.product already uses an internal list, # so this is not a memory regression) output_blocks = output_blocks or list( itertools.product(*[range(dims[i]) for i in out_indices]) ) dsk = {} # Create argument lists for out_coords in output_blocks: deps = set() coords = out_coords + dummies args = [] for cmap, axes, (arg, ind) in zip(coord_maps, concat_axes, argpairs): if ind is None: if deserializing: args.append(stringify_collection_keys(arg)) else: args.append(arg) else: arg_coords = tuple(coords[c] for c in cmap) if axes: tups = lol_product((arg,), arg_coords) if arg not in io_deps: deps.update(flatten(tups)) if concatenate: tups = (concatenate, tups, axes) else: tups = (arg,) + arg_coords if arg not in io_deps: deps.add(tups) # Replace "place-holder" IO keys with "real" args if arg in io_deps: # We don't want to stringify keys for args # we are replacing here idx = tups[1:] args.append(io_deps[arg].get(idx, idx)) elif deserializing: args.append(stringify_collection_keys(tups)) else: args.append(tups) out_key = (output,) + out_coords if deserializing: deps.update(func_future_args) args += list(func_future_args) # Construct a function/args/kwargs dict if we # do not have a nested task (i.e. concatenate=False). # TODO: Avoid using the iterate_collection-version # of to_serialize if we know that are no embedded # Serialized/Serialize objects in args and/or kwargs. if deserializing and isinstance(func, bytes): dsk[out_key] = {"function": func, "args": to_serialize(args)} else: args.insert(0, func) val = tuple(args) # May still need to serialize (if concatenate=True) dsk[out_key] = to_serialize(val) if deserializing else val if return_key_deps: key_deps[out_key] = deps if return_key_deps: # Add valid-key dependencies from io_deps for key, io_dep in io_deps.items(): if io_dep.produces_keys: for out_coords in output_blocks: key = (output,) + out_coords valid_key_dep = io_dep[out_coords] key_deps[key] |= {valid_key_dep} return dsk, key_deps else: return dsk def lol_product(head, values): """List of list of tuple keys, similar to `itertools.product`. Parameters ---------- head : tuple Prefix prepended to all results. values : sequence Mix of singletons and lists. Each list is substituted with every possible value and introduces another level of list in the output. Examples -------- >>> lol_product(('x',), (1, 2, 3)) ('x', 1, 2, 3) >>> lol_product(('x',), (1, [2, 3], 4, [5, 6])) # doctest: +NORMALIZE_WHITESPACE [[('x', 1, 2, 4, 5), ('x', 1, 2, 4, 6)], [('x', 1, 3, 4, 5), ('x', 1, 3, 4, 6)]] """ if not values: return head elif isinstance(values[0], list): return [lol_product(head + (x,), values[1:]) for x in values[0]] else: return lol_product(head + (values[0],), values[1:]) def lol_tuples(head, ind, values, dummies): """List of list of tuple keys Parameters ---------- head : tuple The known tuple so far ind : Iterable An iterable of indices not yet covered values : dict Known values for non-dummy indices dummies : dict Ranges of values for dummy indices Examples -------- >>> lol_tuples(('x',), 'ij', {'i': 1, 'j': 0}, {}) ('x', 1, 0) >>> lol_tuples(('x',), 'ij', {'i': 1}, {'j': range(3)}) [('x', 1, 0), ('x', 1, 1), ('x', 1, 2)] >>> lol_tuples(('x',), 'ijk', {'i': 1}, {'j': [0, 1, 2], 'k': [0, 1]}) # doctest: +NORMALIZE_WHITESPACE [[('x', 1, 0, 0), ('x', 1, 0, 1)], [('x', 1, 1, 0), ('x', 1, 1, 1)], [('x', 1, 2, 0), ('x', 1, 2, 1)]] """ if not ind: return head if ind[0] not in dummies: return lol_tuples(head + (values[ind[0]],), ind[1:], values, dummies) else: return [ lol_tuples(head + (v,), ind[1:], values, dummies) for v in dummies[ind[0]] ] def optimize_blockwise(graph, keys=()): """High level optimization of stacked Blockwise layers For operations that have multiple Blockwise operations one after the other, like ``x.T + 123`` we can fuse these into a single Blockwise operation. This happens before any actual tasks are generated, and so can reduce overhead. This finds groups of Blockwise operations that can be safely fused, and then passes them to ``rewrite_blockwise`` for rewriting. Parameters ---------- graph : HighLevelGraph keys : Iterable The keys of all outputs of all collections. Used to make sure that we don't fuse a layer needed by an output Returns ------- HighLevelGraph See Also -------- rewrite_blockwise """ out = _optimize_blockwise(graph, keys=keys) while out.dependencies != graph.dependencies: graph = out out = _optimize_blockwise(graph, keys=keys) return out def _optimize_blockwise(full_graph, keys=()): keep = {k[0] if type(k) is tuple else k for k in keys} layers = full_graph.layers dependents = reverse_dict(full_graph.dependencies) roots = {k for k in full_graph.layers if not dependents.get(k)} stack = list(roots) out = {} dependencies = {} seen = set() io_names = set() while stack: layer = stack.pop() if layer in seen or layer not in layers: continue seen.add(layer) # Outer loop walks through possible output Blockwise layers if isinstance(layers[layer], Blockwise): blockwise_layers = {layer} deps = set(blockwise_layers) io_names |= layers[layer].io_deps.keys() while deps: # we gather as many sub-layers as we can dep = deps.pop() if dep not in layers: stack.append(dep) continue if not isinstance(layers[dep], Blockwise): stack.append(dep) continue if dep != layer and dep in keep: stack.append(dep) continue if layers[dep].concatenate != layers[layer].concatenate: stack.append(dep) continue if ( sum(k == dep for k, ind in layers[layer].indices if ind is not None) > 1 ): stack.append(dep) continue if blockwise_layers and not _can_fuse_annotations( layers[next(iter(blockwise_layers))].annotations, layers[dep].annotations, ): stack.append(dep) continue # passed everything, proceed blockwise_layers.add(dep) # traverse further to this child's children output_indices = set(layers[dep].output_indices) input_indices = { i for _, ind in layers[dep].indices if ind for i in ind } is_io_superset = output_indices.issuperset(input_indices) for d in full_graph.dependencies.get(dep, ()): # Don't allow reductions to proceed if is_io_superset and len(dependents[d]) <= 1: deps.add(d) else: stack.append(d) # Merge these Blockwise layers into one new_layer = rewrite_blockwise([layers[l] for l in blockwise_layers]) out[layer] = new_layer # Get the new (external) dependencies for this layer. # This corresponds to the dependencies defined in # full_graph.dependencies and are not in blockwise_layers new_deps = set() for l in blockwise_layers: new_deps |= set( { d for d in full_graph.dependencies[l] if d not in blockwise_layers and d in full_graph.dependencies } ) for k, v in new_layer.indices: if v is None: new_deps |= keys_in_tasks(full_graph.dependencies, [k]) elif k not in io_names: new_deps.add(k) dependencies[layer] = new_deps else: out[layer] = layers[layer] dependencies[layer] = full_graph.dependencies.get(layer, set()) stack.extend(full_graph.dependencies.get(layer, ())) return HighLevelGraph(out, dependencies) def _unique_dep(dep, ind): # Append blockwise index information to dependency name return dep + "_" + "_".join(str(i) for i in list(ind)) def _can_fuse_annotations(a: dict | None, b: dict | None) -> bool: """ Treat the special annotation keys, as fusable since we can apply simple rules to capture their intent in a fused layer. """ if a == b: return True if dask.config.get("optimization.annotations.fuse") is False: return False fusable = {"retries", "priority", "resources", "workers", "allow_other_workers"} if (not a or all(k in fusable for k in a)) and ( not b or all(k in fusable for k in b) ): return True return False def _fuse_annotations(*args: dict) -> dict: """ Given an iterable of annotations dictionaries, fuse them according to some simple rules. """ # First, do a basic dict merge -- we are presuming that these have already # been gated by `_can_fuse_annotations`. annotations = toolz.merge(*args) # Max of layer retries retries = [a["retries"] for a in args if "retries" in a] if retries: annotations["retries"] = max(retries) # Max of layer priorities priorities = [a["priority"] for a in args if "priority" in a] if priorities: annotations["priority"] = max(priorities) # Max of all the layer resources resources = [a["resources"] for a in args if "resources" in a] if resources: annotations["resources"] = toolz.merge_with(max, *resources) # Intersection of all the worker restrictions workers = [a["workers"] for a in args if "workers" in a] if workers: annotations["workers"] = list(set.intersection(*[set(w) for w in workers])) # More restrictive of allow_other_workers allow_other_workers = [ a["allow_other_workers"] for a in args if "allow_other_workers" in a ] if allow_other_workers: annotations["allow_other_workers"] = all(allow_other_workers) return annotations def rewrite_blockwise(inputs): """Rewrite a stack of Blockwise expressions into a single blockwise expression Given a set of Blockwise layers, combine them into a single layer. The provided layers are expected to fit well together. That job is handled by ``optimize_blockwise`` Parameters ---------- inputs : list[Blockwise] Returns ------- blockwise: Blockwise See Also -------- optimize_blockwise """ if len(inputs) == 1: # Fast path: if there's only one input we can just use it as-is. return inputs[0] fused_annotations = _fuse_annotations( *[i.annotations for i in inputs if i.annotations] ) inputs = {inp.output: inp for inp in inputs} dependencies = { inp.output: {d for d, v in inp.indices if v is not None and d in inputs} for inp in inputs.values() } dependents = reverse_dict(dependencies) new_index_iter = ( c + (str(d) if d else "") # A, B, ... A1, B1, ... for d in itertools.count() for c in "ABCDEFGHIJKLMNOPQRSTUVWXYZ" ) [root] = [k for k, v in dependents.items() if not v] # Our final results. These will change during fusion below indices = list(inputs[root].indices) new_axes = inputs[root].new_axes concatenate = inputs[root].concatenate dsk = dict(inputs[root].dsk) changed = True while changed: changed = False for i, (dep, ind) in enumerate(indices): if ind is None: continue if dep not in inputs: continue changed = True # Change dep name to avoid fusing the same dep # (in different iteration orders) into a single # subgraph key/dependency # (see: https://github.com/dask/dask/issues/8535) local_dep = dep if dep == root else _unique_dep(dep, ind) # Replace _n with dep name in existing tasks # (inc, _0) -> (inc, 'b') dsk = {k: subs(v, {blockwise_token(i): local_dep}) for k, v in dsk.items()} # Remove current input from input indices # [('a', 'i'), ('b', 'i')] -> [('a', 'i')] _, current_dep_indices = indices.pop(i) sub = { blockwise_token(i): blockwise_token(i - 1) for i in range(i + 1, len(indices) + 1) } dsk = subs(dsk, sub) # Change new input_indices to match give index from current computation # [('c', j')] -> [('c', 'i')] new_indices = inputs[dep].indices sub = dict(zip(inputs[dep].output_indices, current_dep_indices)) contracted = { x for _, j in new_indices if j is not None for x in j if x not in inputs[dep].output_indices } extra = dict(zip(contracted, new_index_iter)) sub.update(extra) new_indices = [(x, index_subs(j, sub)) for x, j in new_indices] # Update new_axes for k, v in inputs[dep].new_axes.items(): new_axes[sub[k]] = v # Bump new inputs up in list sub = {} # Map from (id(key), inds or None) -> index in indices. Used to deduplicate indices. index_map = {(id(k), inds): n for n, (k, inds) in enumerate(indices)} for ii, index in enumerate(new_indices): id_key = (id(index[0]), index[1]) if id_key in index_map: # use old inputs if available sub[blockwise_token(ii)] = blockwise_token(index_map[id_key]) else: index_map[id_key] = len(indices) sub[blockwise_token(ii)] = blockwise_token(len(indices)) indices.append(index) new_dsk = subs(inputs[dep].dsk, sub) # Change new_dsk key to match local_dep if dep != local_dep and dep in new_dsk: new_dsk[local_dep] = new_dsk.pop(dep) # indices.extend(new_indices) dsk.update(new_dsk) # De-duplicate indices like [(a, ij), (b, i), (a, ij)] -> [(a, ij), (b, i)] # Make sure that we map everything else appropriately as we remove inputs new_indices = [] seen = {} sub = {} # like {_0: _0, _1: _0, _2: _1} for i, x in enumerate(indices): if x[1] is not None and x in seen: sub[i] = seen[x] else: if x[1] is not None: seen[x] = len(new_indices) sub[i] = len(new_indices) new_indices.append(x) sub = {blockwise_token(k): blockwise_token(v) for k, v in sub.items()} dsk = {k: subs(v, sub) for k, v in dsk.items() if k not in sub.keys()} indices_check = {k for k, v in indices if v is not None} numblocks = toolz.merge([inp.numblocks for inp in inputs.values()]) numblocks = {k: v for k, v in numblocks.items() if v is None or k in indices_check} # Update IO-dependency information io_deps = {} for v in inputs.values(): io_deps.update(v.io_deps) return Blockwise( root, inputs[root].output_indices, dsk, new_indices, numblocks=numblocks, new_axes=new_axes, concatenate=concatenate, annotations=fused_annotations, io_deps=io_deps, ) @_deprecated() def zero_broadcast_dimensions(lol, nblocks): """ >>> lol = [('x', 1, 0), ('x', 1, 1), ('x', 1, 2)] >>> nblocks = (4, 1, 2) # note singleton dimension in second place >>> lol = [[('x', 1, 0, 0), ('x', 1, 0, 1)], ... [('x', 1, 1, 0), ('x', 1, 1, 1)], ... [('x', 1, 2, 0), ('x', 1, 2, 1)]] >>> zero_broadcast_dimensions(lol, nblocks) # doctest: +SKIP [[('x', 1, 0, 0), ('x', 1, 0, 1)], [('x', 1, 0, 0), ('x', 1, 0, 1)], [('x', 1, 0, 0), ('x', 1, 0, 1)]] See Also -------- lol_tuples """ f = lambda t: (t[0],) + tuple(0 if d == 1 else i for i, d in zip(t[1:], nblocks)) return homogeneous_deepmap(f, lol) def broadcast_dimensions(argpairs, numblocks, sentinels=(1, (1,)), consolidate=None): """Find block dimensions from arguments Parameters ---------- argpairs : iterable name, ijk index pairs numblocks : dict maps {name: number of blocks} sentinels : iterable (optional) values for singleton dimensions consolidate : func (optional) use this to reduce each set of common blocks into a smaller set Examples -------- >>> argpairs = [('x', 'ij'), ('y', 'ji')] >>> numblocks = {'x': (2, 3), 'y': (3, 2)} >>> broadcast_dimensions(argpairs, numblocks) {'i': 2, 'j': 3} Supports numpy broadcasting rules >>> argpairs = [('x', 'ij'), ('y', 'ij')] >>> numblocks = {'x': (2, 1), 'y': (1, 3)} >>> broadcast_dimensions(argpairs, numblocks) {'i': 2, 'j': 3} Works in other contexts too >>> argpairs = [('x', 'ij'), ('y', 'ij')] >>> d = {'x': ('Hello', 1), 'y': (1, (2, 3))} >>> broadcast_dimensions(argpairs, d) {'i': 'Hello', 'j': (2, 3)} """ # List like [('i', 2), ('j', 1), ('i', 1), ('j', 2)] argpairs2 = [(a, ind) for a, ind in argpairs if ind is not None] L = toolz.concat( [ zip(inds, dims) for (x, inds), (x, dims) in toolz.join( toolz.first, argpairs2, toolz.first, numblocks.items() ) ] ) g = toolz.groupby(0, L) g = {k: {d for i, d in v} for k, v in g.items()} g2 = {k: v - set(sentinels) if len(v) > 1 else v for k, v in g.items()} if consolidate: return toolz.valmap(consolidate, g2) if g2 and not set(map(len, g2.values())) == {1}: raise ValueError("Shapes do not align %s" % g) return toolz.valmap(toolz.first, g2) def _make_dims(indices, numblocks, new_axes): """Returns a dictionary mapping between each index specified in `indices` and the number of output blocks for that indice. """ dims = broadcast_dimensions(indices, numblocks) for k, v in new_axes.items(): dims[k] = len(v) if isinstance(v, tuple) else 1 return dims def fuse_roots(graph: HighLevelGraph, keys: list): """ Fuse nearby layers if they don't have dependencies Often Blockwise sections of the graph fill out all of the computation except for the initial data access or data loading layers:: Large Blockwise Layer | | | X Y Z This can be troublesome because X, Y, and Z tasks may be executed on different machines, and then require communication to move around. This optimization identifies this situation, lowers all of the graphs to concrete dicts, and then calls ``fuse`` on them, with a width equal to the number of layers like X, Y, and Z. This is currently used within array and dataframe optimizations. Parameters ---------- graph : HighLevelGraph The full graph of the computation keys : list The output keys of the computation, to be passed on to fuse See Also -------- Blockwise fuse """ layers = ensure_dict(graph.layers, copy=True) dependencies = ensure_dict(graph.dependencies, copy=True) dependents = reverse_dict(dependencies) for name, layer in graph.layers.items(): deps = graph.dependencies[name] if ( isinstance(layer, Blockwise) and len(deps) > 1 and not any(dependencies[dep] for dep in deps) # no need to fuse if 0 or 1 and all(len(dependents[dep]) == 1 for dep in deps) and all(layer.annotations == graph.layers[dep].annotations for dep in deps) ): new = toolz.merge(layer, *[layers[dep] for dep in deps]) new, _ = fuse(new, keys, ave_width=len(deps)) for dep in deps: del layers[dep] del dependencies[dep] layers[name] = new dependencies[name] = set() return HighLevelGraph(layers, dependencies)