Classe « DataFrame »

Méthode pandas.DataFrame.set_index

Signature de la méthode set_index

def set_index(self, keys, drop=True, append=False, inplace=False, verify_integrity=False) 

Description

set_index.__doc__

        Set the DataFrame index using existing columns.

        Set the DataFrame index (row labels) using one or more existing
        columns or arrays (of the correct length). The index can replace the
        existing index or expand on it.

        Parameters
        ----------
        keys : label or array-like or list of labels/arrays
            This parameter can be either a single column key, a single array of
            the same length as the calling DataFrame, or a list containing an
            arbitrary combination of column keys and arrays. Here, "array"
            encompasses :class:`Series`, :class:`Index`, ``np.ndarray``, and
            instances of :class:`~collections.abc.Iterator`.
        drop : bool, default True
            Delete columns to be used as the new index.
        append : bool, default False
            Whether to append columns to existing index.
        inplace : bool, default False
            If True, modifies the DataFrame in place (do not create a new object).
        verify_integrity : bool, default False
            Check the new index for duplicates. Otherwise defer the check until
            necessary. Setting to False will improve the performance of this
            method.

        Returns
        -------
        DataFrame or None
            Changed row labels or None if ``inplace=True``.

        See Also
        --------
        DataFrame.reset_index : Opposite of set_index.
        DataFrame.reindex : Change to new indices or expand indices.
        DataFrame.reindex_like : Change to same indices as other DataFrame.

        Examples
        --------
        >>> df = pd.DataFrame({'month': [1, 4, 7, 10],
        ...                    'year': [2012, 2014, 2013, 2014],
        ...                    'sale': [55, 40, 84, 31]})
        >>> df
           month  year  sale
        0      1  2012    55
        1      4  2014    40
        2      7  2013    84
        3     10  2014    31

        Set the index to become the 'month' column:

        >>> df.set_index('month')
               year  sale
        month
        1      2012    55
        4      2014    40
        7      2013    84
        10     2014    31

        Create a MultiIndex using columns 'year' and 'month':

        >>> df.set_index(['year', 'month'])
                    sale
        year  month
        2012  1     55
        2014  4     40
        2013  7     84
        2014  10    31

        Create a MultiIndex using an Index and a column:

        >>> df.set_index([pd.Index([1, 2, 3, 4]), 'year'])
                 month  sale
           year
        1  2012  1      55
        2  2014  4      40
        3  2013  7      84
        4  2014  10     31

        Create a MultiIndex using two Series:

        >>> s = pd.Series([1, 2, 3, 4])
        >>> df.set_index([s, s**2])
              month  year  sale
        1 1       1  2012    55
        2 4       4  2014    40
        3 9       7  2013    84
        4 16     10  2014    31