Preprocessing onehotencoder featurenames

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OneHotEncoder.FeatureNames

The name of each column the encoder produces, get_feature_names_out.

public string[] FeatureNames(IReadOnlyList<string> inputFeatures = null)

Parameters — inputFeatures is one name per input feature; null names them x0, x1, …, as the reference does for an array.

Returns — feature_category for each column, in the columns' order, and feature_infrequent_sklearn for a feature's infrequent column.

Exceptions — ArgumentException when inputFeatures does not hold FeatureCount names.

Example — two frequent categories and the column the rest share.

using Lodestar.Preprocessing;

OneHotEncoder<string> encoder = Encoders.OneHot(
    ["a", "a", "a", "b", "b", "c", "d"], 1, new OneHotEncoderOptions { MinFrequency = 2 });

string names = string.Join(",", encoder.FeatureNames(["colour"]));  // => colour_a,colour_b,colour_infrequent_sklearn

Remarks — a category is written as Python's str writes it: a string as it is, an integer in invariant digits, a floating value as 1.0 or 1e-05. A dropped column has no name, as it has no column.

Applies to — net10.0, netstandard2.0.

See also — OneHotEncoder, OneHotEncoderOptions.