ak.from_buffers
Defined in awkward.operations.convert on line 4990.
- ak.from_buffers(form, length, container, partition_start=0, key_format='part{partition}-{form_key}-{attribute}', lazy=False, lazy_cache='new', lazy_cache_key=None, highlevel=True, behavior=None)
- Parameters:
form (
ak.forms.Formor str/dict equivalent) – The form of the Awkward Array to reconstitute from named buffers.length (int or iterable of int) – Length of the array to reconstitute as a non-partitioned array or the lengths (plural) of partitions in a partitioned array.
container (Mapping, such as dict) – The str → Python buffers that represent the decomposed Awkward Array. This
containeris only assumed to have a__getitem__method that accepts strings as keys.partition_start (int) – First (or only) partition number to get from the
container.key_format (str or callable) – Python format string containing
"{partition}","{form_key}", and/or"{attribute}"or a function that takes these as keyword arguments and returns a string to use as keys for buffers in thecontainer. Thepartitionis a partition number (non-negative integer, passed as a string), theform_keyis a string associated with each node in the Form, and theattributeis a hard-coded string representing the buffer’s function (e.g."data","offsets","index").lazy (bool) – If True, read the array or its partitions on demand (as
ak.layout.VirtualArray, possibly inak.partition.PartitionedArrayifnum_partitionsis not None); if False, read all requested data immediately. Any RecordArray child nodes will additionally be read on demand.lazy_cache (None, "new", or MutableMapping) – If lazy, pass this cache to the VirtualArrays. If “new”, a new dict (keep-forever cache) is created. If None, no cache is used.
lazy_cache_key (None or str) – If lazy, pass this cache_key to the VirtualArrays. If None, a process-unique string is constructed.
highlevel (bool) – If True, return an
ak.Array; otherwise, return a low-levelak.layout.Contentsubclass.behavior (None or dict) – Custom
ak.behaviorfor the output array, if high-level.
Reconstitutes an Awkward Array from a Form, length, and a collection of memory buffers, so that data can be losslessly read from file formats and storage devices that only map names to binary blobs (such as a filesystem directory).
The first three arguments of this function are the return values of
ak.to_buffers, so a full round-trip is
>>> reconstituted = ak.from_buffers(*ak.to_buffers(original))
The container argument lets you specify your own Mapping, which might be
an interface to some storage format or device (e.g. h5py). It’s okay if
the container dropped NumPy’s dtype and shape information, leaving
raw bytes, since dtype and shape can be reconstituted from the
ak.forms.NumpyForm.
The key_format should be the same as the one used in ak.to_buffers.
The arguments that begin with lazy_ are only needed if lazy is True.
The lazy_cache and lazy_cache_key determine how the array or its
partitions are cached after being read from the container (in a no-eviction
dict attached to the output ak.Array as cache if not specified).
See ak.to_buffers for examples.