ak.str.to_categorical

Defined in awkward.operations.str.akstr_to_categorical on line 13.

ak.str.to_categorical(array, *, highlevel=True, behavior=None, attrs=None)

Parameters:

• array – Array-like data (anything ak.to_layout recognizes).

• highlevel (bool) – If True, return an ak.Array; otherwise, return a low-level ak.contents.Content subclass.

• behavior (None or dict) – Custom ak.behavior for the output array, if high-level.

• attrs (None or dict) – Custom attributes for the output array, if high-level.

Returns a dictionary-encoded version of the given array of strings. Creates a categorical dataset, which has the following properties:

• only distinct values (categories) are stored in their entirety,

• pointers to those distinct values are represented by integers (an ak.contents.IndexedArray or ak.contents.IndexedOptionArray labeled with parameter "__array__" = "categorical".

This is equivalent to R’s “factor”, and Pandas’s “categorical”. It differs from generic uses of ak.contents.IndexedArray and ak.contents.IndexedOptionArray in Awkward Arrays by the guarantee of no duplicate categories and the "categorical" parameter.

Unlike Arrow’s dictionary_encode, this function has no null_handling argument. This function’s behavior is like``null_handling=”mask”`` (Arrow’s default). It is not possible to encode null values in Awkward Array, as ak.contents.IndexedOptionArray cannot contain an option type node.

Note: this function does not raise an error if the array does not contain any string or bytestring data.

Requires the pyarrow library and calls pyarrow.compute.dictionary_encode.