classmethod Categorical.from_codes(codes, categories=None, ordered=None, dtype=None)[source]

Make a Categorical type from codes and categories or dtype.

This constructor is useful if you already have codes and categories/dtype and so do not need the (computation intensive) factorization step, which is usually done on the constructor.

If your data does not follow this convention, please use the normal constructor.

codes : array-like, integers

An integer array, where each integer points to a category in categories or dtype.categories, or else is -1 for NaN

categories : index-like, optional

The categories for the categorical. Items need to be unique. If the categories are not given here, then they must be provided in dtype.

ordered : bool, optional

Whether or not this categorical is treated as an ordered categorical. If not given here or in dtype, the resulting categorical will be unordered.

dtype : CategoricalDtype or the string “category”, optional

If CategoricalDtype, cannot be used together with categories or ordered.

New in version 0.24.0: When dtype is provided, neither categories nor ordered should be provided.


>>> dtype = pd.CategoricalDtype(['a', 'b'], ordered=True)
>>> pd.Categorical.from_codes(codes=[0, 1, 0, 1], dtype=dtype)
[a, b, a, b]
Categories (2, object): [a < b]
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