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# pandas.errors.MergeError

exception pandas.errors.MergeError

  Exception raised when merging data.

  Subclass of `ValueError`.

  Examples

      >>> left = pd.DataFrame({"a": ["a", "b", "b", "d"],
      ...                     "b": ["cat", "dog", "weasel", "horse"]},
      ...                     index=range(4))
      >>> right = pd.DataFrame({"a": ["a", "b", "c", "d"],
      ...                      "c": ["meow", "bark", "chirp", "nay"]},
      ...                      index=range(4)).set_index("a")
      >>> left.join(right, on="a", validate="one_to_one",)
      Traceback (most recent call last):
      MergeError: Merge keys are not unique in left dataset; not a one-to-one merge