Class MergeError

pandas/errors/__init__.py:435–463

Exception raised when merging data. Subclass of ``ValueError``. See Also -------- DataFrame.join : For joining DataFrames on their indexes. merge : For merging two DataFrames on a common set of keys. Examples -------- >>> left = pd.DataFrame( ... {"a":

class MergeError(ValueError):
    """
    Exception raised when merging data.

    Subclass of ``ValueError``.

    See Also
    --------
    DataFrame.join : For joining DataFrames on their indexes.
    merge : For merging two DataFrames on a common set of keys.

    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
    """


class AbstractMethodError(NotImplementedError):