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# pandas.Index.map

Index.map(mapper, na_action=None)

  Map values using an input mapping or function.

  Applies a function, dict, or Series to each element of the Index, returning a new Index (or MultiIndex if tuples are returned).

  Parameters:
    mapper function, dict, or Series

      Mapping correspondence.

    na_action{None, ‘ignore’}

      If ‘ignore’, propagate NA values, without passing them to the mapping correspondence.

  Returns:
    Union[Index, MultiIndex]

      The output of the mapping function applied to the index. If the function returns a tuple with more than one element a MultiIndex will be returned.

  See also

  `Index.where`

    Replace values where the condition is False.

  Examples

      >>> idx = pd.Index([1, 2, 3])
      >>> idx.map({1: "a", 2: "b", 3: "c"})
      Index(['a', 'b', 'c'], dtype='str')

  Using map with a function:

      >>> idx = pd.Index([1, 2, 3])
      >>> idx.map("I am a {}".format)
      Index(['I am a 1', 'I am a 2', 'I am a 3'], dtype='str')

      >>> idx = pd.Index(["a", "b", "c"])
      >>> idx.map(lambda x: x.upper())
      Index(['A', 'B', 'C'], dtype='str')