Method get_slice_bound

pandas/core/indexes/base.py:6912–6998

Calculate slice bound that corresponds to given label. Returns leftmost (one-past-the-rightmost if ``side=='right'``) position of given label. Parameters ---------- label : object The label for which to calculate the slice bound.

(self, label, side: Literal["left", "right"])

        raise ValueError("index must be monotonic increasing or decreasing")

    def get_slice_bound(self, label, side: Literal["left", "right"]) -> int:
        """
        Calculate slice bound that corresponds to given label.

        Returns leftmost (one-past-the-rightmost if ``side=='right'``) position
        of given label.

        Parameters
        ----------
        label : object
            The label for which to calculate the slice bound.
        side : {'left', 'right'}
            if 'left' return leftmost position of given label.
            if 'right' return one-past-the-rightmost position of given label.

        Returns
        -------
        int
            Index of label.

        See Also
        --------
        Index.get_loc : Get integer location, slice or boolean mask for requested
            label.

        Examples
        --------
        >>> idx = pd.RangeIndex(5)
        >>> idx.get_slice_bound(3, "left")
        3

        >>> idx.get_slice_bound(3, "right")
        4

        If ``label`` is non-unique in the index, an error will be raised.

        >>> idx_duplicate = pd.Index(["a", "b", "a", "c", "d"])
        >>> idx_duplicate.get_slice_bound("a", "left")
        Traceback (most recent call last):
        KeyError: Cannot get left slice bound for non-unique label: 'a'
        """

        if side not in ("left", "right"):
            raise ValueError(
                "Invalid value for side kwarg, must be either "
                f"'left' or 'right': {side}"
            )

        original_label = label

        # For datetime indices label may be a string that has to be converted
        # to datetime boundary according to its resolution.
        label = self._maybe_cast_slice_bound(label, side)

        # we need to look up the label
        try:
            slc = self.get_loc(label)
        except KeyError: