Method duplicated

pandas/core/series.py:2347–2425

Indicate duplicate Series values. Duplicated values are indicated as ``True`` values in the resulting Series. Either all duplicates, all except the first or all except the last occurrence of duplicates can be indicated. Parameters ----------

(self, keep: DropKeep = "first")

            return result

    def duplicated(self, keep: DropKeep = "first") -> Series:
        """
        Indicate duplicate Series values.

        Duplicated values are indicated as ``True`` values in the resulting
        Series. Either all duplicates, all except the first or all except the
        last occurrence of duplicates can be indicated.

        Parameters
        ----------
        keep : {'first', 'last', False}, default 'first'
            Method to handle dropping duplicates:

            - 'first' : Mark duplicates as ``True`` except for the first
              occurrence.
            - 'last' : Mark duplicates as ``True`` except for the last
              occurrence.
            - ``False`` : Mark all duplicates as ``True``.

        Returns
        -------
        Series[bool]
            Series indicating whether each value has occurred in the
            preceding values.

        See Also
        --------
        Index.duplicated : Equivalent method on pandas.Index.
        DataFrame.duplicated : Equivalent method on pandas.DataFrame.
        Series.drop_duplicates : Remove duplicate values from Series.

        Examples
        --------
        By default, for each set of duplicated values, the first occurrence is
        set on False and all others on True:

        >>> animals = pd.Series(["llama", "cow", "llama", "beetle", "llama"])
        >>> animals.duplicated()
        0    False
        1    False
        2     True
        3    False
        4     True
        dtype: bool

        which is equivalent to

        >>> animals.duplicated(keep="first")
        0    False
        1    False
        2     True
        3    False
        4     True
        dtype: bool

        By using 'last', the last occurrence of each set of duplicated values
        is set on False and all others on True: