def test_get_name_from_key():
# Arbitrary hashables
h1 = object()
h2 = object()
assert get_name_from_key("foo") == "foo"
assert get_name_from_key("foo-123"), "foo-123"
assert get_name_from_key(("foo-123", h1, h2)) == "foo-123"
with pytest.raises(TypeError):
get_name_from_key(1)
with pytest.raises(TypeError):
get_name_from_key(())
with pytest.raises(TypeError):
get_name_from_key((1, ))
def _build_map_layer(
func: Callable,
prev_name: str,
new_name: str,
collection,
dependencies: tuple[Delayed, ...] = (),
) -> Layer:
"""Apply func to all keys of collection. Create a Blockwise layer whenever possible;
fall back to MaterializedLayer otherwise.
Parameters
----------
func
Callable to be invoked on the graph node
prev_name : str
name of the layer to map from; in case of dask base collections, this is the
collection name. Note how third-party collections, e.g. xarray.Dataset, can
have multiple names.
new_name : str
name of the layer to map to
collection
Arbitrary dask collection
dependencies
Zero or more Delayed objects, which will be passed as arbitrary variadic args to
func after the collection's chunk
"""
if _can_apply_blockwise(collection):
# Use a Blockwise layer
try:
numblocks = collection.numblocks
except AttributeError:
numblocks = (collection.npartitions, )
indices = tuple(i for i, _ in enumerate(numblocks))
kwargs = {
"_deps": [d.key for d in dependencies]
} if dependencies else {}
return blockwise(
func,
new_name,
indices,
prev_name,
indices,
numblocks={prev_name: numblocks},
dependencies=dependencies,
**kwargs,
)
else:
# Delayed, bag.Item, dataframe.core.Scalar, or third-party collection;
# fall back to MaterializedLayer
dep_keys = tuple(d.key for d in dependencies)
return MaterializedLayer({
replace_name_in_key(k, {prev_name: new_name}): (func, k) + dep_keys
for k in flatten(collection.__dask_keys__())
if get_name_from_key(k) == prev_name
})