Method left_error_msg

pandas/core/reshape/merge.py:1980–1983

(x: Index)

            right_unique = right_join_index.is_unique

        def left_error_msg(x: Index) -> str:
            name = self.left_on if not self.left_index else lib.no_default
            msg = x[x.duplicated()][:5].to_frame(name=name).to_string(index=False)
            return f"\nDuplicates in left:\n {msg} ..."

        def right_error_msg(x: Index) -> str:
            name = self.right_on if not self.right_index else lib.no_default