Method reindex

pandas/core/indexes/base.py:4147–4258

Create index with target's values. Parameters ---------- target : an iterable An iterable containing the values to be used for creating the new index. method : {None, 'pad'/'ffill', 'backfill'/'bfill', 'nearest'}, optional * default:

(
        self,
        target,
        method: ReindexMethod | None = None,
        level=None,
        limit: int | None = None,
        tolerance: float | None = None,
    )

            raise ValueError("cannot reindex on an axis with duplicate labels")

    def reindex(
        self,
        target,
        method: ReindexMethod | None = None,
        level=None,
        limit: int | None = None,
        tolerance: float | None = None,
    ) -> tuple[Index, npt.NDArray[np.intp] | None]:
        """
        Create index with target's values.

        Parameters
        ----------
        target : an iterable
            An iterable containing the values to be used for creating the new index.
        method : {None, 'pad'/'ffill', 'backfill'/'bfill', 'nearest'}, optional
            * default: exact matches only.
            * pad / ffill: find the PREVIOUS index value if no exact match.
            * backfill / bfill: use NEXT index value if no exact match
            * nearest: use the NEAREST index value if no exact match. Tied
              distances are broken by preferring the larger index value.
        level : int, optional
            Level of multiindex.
        limit : int, optional
            Maximum number of consecutive labels in ``target`` to match for
            inexact matches.
        tolerance : int, float, or list-like, optional
            Maximum distance between original and new labels for inexact
            matches. The values of the index at the matching locations must
            satisfy the equation ``abs(index[indexer] - target) <= tolerance``.

            Tolerance may be a scalar value, which applies the same tolerance
            to all values, or list-like, which applies variable tolerance per
            element. List-like includes list, tuple, array, Series, and must be
            the same size as the index and its dtype must exactly match the
            index&#x27;s type.

        Returns
        -------
        new_index : pd.Index
            Resulting index.
        indexer : np.ndarray[np.intp] or None
            Indices of output values in original index.

        Raises
        ------
        TypeError
            If ``method`` passed along with ``level``.
        ValueError
            If non-unique multi-index
        ValueError
            If non-unique index and ``method`` or ``limit`` passed.

        See Also
        --------
        Series.reindex : Conform Series to new index with optional filling logic.
        DataFrame.reindex : Conform DataFrame to new index with optional filling logic.