_set_index¶

pyhelpers.store._set_index(data, index=None)[source]¶

Sets the index of a dataframe.

Parameters:

data (pandas.DataFrame) – The dataframe to update.
index (int | list | None) – Column index or a list of column indices to set as the index; when index=None (default), the function sets the first column as the index if its column name is an empty string.

Returns:

The dataframe with the updated index.

Return type:

pandas.DataFrame

Tests:

>>> from pyhelpers.store import _set_index
>>> from pyhelpers._cache import example_dataframe
>>> import numpy as np
>>> example_df = example_dataframe()
>>> example_df
            Longitude   Latitude
City
London      -0.127647  51.507322
Birmingham  -1.902691  52.479699
Manchester  -2.245115  53.479489
Leeds       -1.543794  53.797418
>>> example_df.equals(_set_index(example_df))
True
>>> example_df_1 = _set_index(example_df, index=0)
>>> example_df_1
            Latitude
Longitude
-0.127647  51.507322
-1.902691  52.479699
-2.245115  53.479489
-1.543794  53.797418
>>> example_df.iloc[:, 0].to_list() == example_df_1.index.to_list()
True
>>> example_df_2 = example_df.copy()
>>> example_df_2.index.name = ''
>>> example_df_2.reset_index(inplace=True)
>>> example_df_2 = _set_index(example_df_2, index=None)
>>> np.array_equal(example_df_2.values, example_df.values)
True