dtoolkit.transformer.FillnaTF#

class dtoolkit.transformer.FillnaTF(*args, **kwargs)[source]#

A transformer could fill NA/NaN values using the specified method.

See also

pandas.DataFrame.fillna: This transformer’s prototype method.

Notes

fillna()’s inplace parameter is not work for this transformer. Actually this break pipeline stream. If a transformer’s inplace is True, the next tf input would get None.

Examples

>>> import numpy as np
>>> import pandas as pd
>>> from dtoolkit.transformer import FillnaTF
>>> df = pd.DataFrame(
...     [
...         [np.nan, 2, np.nan, 0],
...         [3, 4, np.nan, 1],
...         [np.nan, np.nan, np.nan, 5],
...         [np.nan, 3, np.nan, 4],
...     ],
...     columns=list('ABCD'),
... )
>>> df
    A    B   C  D
0  NaN  2.0 NaN  0
1  3.0  4.0 NaN  1
2  NaN  NaN NaN  5
3  NaN  3.0 NaN  4

Replace all NaN elements with 0s.

>>> tf = FillnaTF(0)
>>> tf.transform(df)
    A   B   C   D
0   0.0 2.0 0.0 0
1   3.0 4.0 0.0 1
2   0.0 0.0 0.0 5
3   0.0 3.0 0.0 4

We can also propagate non-null values forward or backward.

>>> tf = FillnaTF(method='ffill')
>>> tf.transform(df)
    A   B   C   D
0   NaN 2.0 NaN 0
1   3.0 4.0 NaN 1
2   3.0 4.0 NaN 5
3   3.0 3.0 NaN 4

Replace all NaN elements in column ‘A’, ‘B’, ‘C’, and ‘D’, with 0, 1, 2, and 3 respectively.

>>> values = {'A': 0, 'B': 1, 'C': 2, 'D': 3}
>>> tf = FillnaTF(value=values)
>>> tf.transform(df)
    A   B   C   D
0   0.0 2.0 2.0 0
1   3.0 4.0 2.0 1
2   0.0 1.0 2.0 5
3   0.0 3.0 2.0 4

Only replace the first NaN element.

>>> tf = FillnaTF(value=values, limit=1)
>>> tf.transform(df)
    A   B   C   D
0   0.0 2.0 2.0 0
1   3.0 4.0 NaN 1
2   NaN 1.0 NaN 5
3   NaN 3.0 NaN 4

Attributes:

inverse_transform_method

Methods

`fit`(*_)	Fit transformer.
`fit_transform`(X[, y])	Fit to data, then transform it.
`inverse_transform`(X)	Undo transform to `X`.
`set_output`(*[, transform])	Set output container.
`transform`(X)	Transform `X`.
`transform_method`(self[, value, method, ...])	Fill NA/NaN values using the specified method.
`update_invargs`(args, *kwargs)	Inverse transform method argument entry.