Added case for no kwargs match

Author: konstantinstadler

pymrio/tools/ioutil.py

@@ -950,6 +950,7 @@ def _index_regex_matcher(_dfs_idx, _method, _find_all=None, **kwargs):
         else:
             return _dfs_idx[found]
 
+    at_least_one_valid = False
     for key, value in kwargs.items():
         try:
             if type(_dfs_idx) in [pd.DataFrame, pd.Series]:
@@ -962,7 +963,14 @@ def _index_regex_matcher(_dfs_idx, _method, _find_all=None, **kwargs):
                     "pd.DataFrame, pd.Series, pd.Index or pd.MultiIndex"
                 )
             _dfs_idx = _dfs_idx[fun(value, case=True, flags=0, na=False)]
+            at_least_one_valid = True
         except KeyError:
             pass
 
+    if not at_least_one_valid:
+        if type(_dfs_idx) in [pd.DataFrame, pd.Series]:
+            _dfs_idx = pd.DataFrame(index=[], columns=_dfs_idx.columns)            
+        elif type(_dfs_idx) in [pd.Index, pd.MultiIndex]:
+            _dfs_idx = pd.Index([])
+
     return _dfs_idx

tests/test_util.py

@@ -339,3 +339,14 @@ def test_util_regex():
     # 5. test wrong input
     with pytest.raises(ValueError):
         index_fullmatch("foo", region="a.*", sector=".*b.*", not_present_column="abc")
+
+    # 6. test with all kwargs not present
+
+    df_some_match = index_match(test_df, region="a.*", sector=".*b.*", not_present_column="abc")
+    assert df_some_match.index.get_level_values("region").unique() == ["a1"]
+    assert df_some_match.index.get_level_values("sector").unique() == ["bb"]
+
+    df_none_match = index_match(test_df, not_present_column="abc")
+    df_none_match_index = index_contains(test_index, not_present_column="abc")
+    assert len(df_none_match) == 0
+    assert len(df_none_match_index) == 0