DOC: Fix reference to rows in read_csv(index_col) error message (pandas-dev#57991)

* Fix reference to rows in `read_csv(index_col)` warning message

* test - update expected error message

* accept

Co-authored-by: Matthew Roeschke <[email protected]>

* accept

Co-authored-by: Matthew Roeschke <[email protected]>

---------

Co-authored-by: Matthew Roeschke <[email protected]>

Author: 2 people

pandas/io/parsers/base_parser.py

@@ -174,7 +174,7 @@ def __init__(self, kwds) -> None:
                     and all(map(is_integer, self.index_col))
                 ):
                     raise ValueError(
-                        "index_col must only contain row numbers "
+                        "index_col must only contain integers of column positions "
                         "when specifying a multi-index header"
                     )
                 else:

pandas/tests/io/parser/test_header.py

@@ -162,7 +162,7 @@ def test_header_multi_index(all_parsers):
             {"index_col": ["foo", "bar"]},
             (
                 "index_col must only contain "
-                "row numbers when specifying "
+                "integers of column positions when specifying "
                 "a multi-index header"
             ),
         ),