pyarrow.dataset.DirectoryPartitioning

class pyarrow.dataset.DirectoryPartitioning

Bases: pyarrow._dataset.Partitioning

A Partitioning based on a specified Schema.

The DirectoryPartitioning expects one segment in the file path for each field in the schema (all fields are required to be present). For example given schema<year:int16, month:int8> the path “/2009/11” would be parsed to (“year”_ == 2009 and “month”_ == 11).

Parameters

  • schema (Schema) – The schema that describes the partitions present in the file path.

  • dictionaries (Dict[str, Array]) – If the type of any field of schema is a dictionary type, the corresponding entry of dictionaries must be an array containing every value which may be taken by the corresponding column or an error will be raised in parsing.

Returns

DirectoryPartitioning

Examples

>>> from pyarrow.dataset import DirectoryPartitioning
>>> partition = DirectoryPartitioning(
...     pa.schema([("year", pa.int16()), ("month", pa.int8())]))
>>> print(partitioning.parse("/2009/11"))
((year == 2009:int16) and (month == 11:int8))
__init__(*args, **kwargs)

Initialize self. See help(type(self)) for accurate signature.

Methods

__init__(*args, **kwargs)

Initialize self.

discover

Discover a DirectoryPartitioning.

parse

Attributes

schema

The arrow Schema attached to the partitioning.
static discover()

Discover a DirectoryPartitioning.

Parameters

  • field_names (list of str) – The names to associate with the values from the subdirectory names.

  • infer_dictionary (bool, default False) – When inferring a schema for partition fields, yield dictionary encoded types instead of plain types. This can be more efficient when materializing virtual columns, and Expressions parsed by the finished Partitioning will include dictionaries of all unique inspected values for each field.

  • max_partition_dictionary_size (int, default 0) – Synonymous with infer_dictionary for backwards compatibility with 1.0: setting this to -1 or None is equivalent to passing infer_dictionary=True.

Returns

DirectoryPartitioningFactory – To be used in the FileSystemFactoryOptions.

parse()
schema

The arrow Schema attached to the partitioning.