pandas.errors.MergeError — pandas 2.2.3 documentation (original) (raw)

exception pandas.errors.MergeError[source]#

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