BUG: Fix read_json shape error on multi-indexed DF/SR with orient='split' pandas-dev#4889

Author: LucasG0

pandas/io/json/_json.py

@@ -1004,6 +1004,8 @@ def _parse_no_numpy(self):
         if self.orient == "split":
             decoded = {str(k): v for k, v in data.items()}
             self.check_keys_split(decoded)
+            if "index" in decoded:
+                decoded["index"] = np.transpose(decoded["index"]).tolist()
             self.obj = create_series_with_explicit_dtype(**decoded)
         else:
             self.obj = create_series_with_explicit_dtype(data, dtype_if_empty=object)
@@ -1095,6 +1097,8 @@ def _parse_no_numpy(self):
                 for k, v in loads(json, precise_float=self.precise_float).items()
             }
             self.check_keys_split(decoded)
+            if "index" in decoded:
+                decoded["index"] = np.transpose(decoded["index"]).tolist()
             self.obj = DataFrame(dtype=None, **decoded)
         elif orient == "index":
             self.obj = DataFrame.from_dict(

pandas/tests/io/json/test_pandas.py

@@ -1394,6 +1394,22 @@ def test_index_false_to_json_split(self, data, expected):
 
         assert result == expected
 
+    def test_read_json_frame_mutltiindex_split(self):
+        index = pd.MultiIndex.from_tuples([(1, 1), (2, 1), (1, 2), (2, 2)])
+        expected = pd.DataFrame(
+            data=[[1, 1], [2, 2], [3, 3], [4, 4]], columns=["A", "B"], index=index
+        )
+        js = expected.to_json(orient="split")
+        result = pd.read_json(js, orient="split")
+        tm.assert_frame_equal(expected, result)
+
+    def test_read_json_series_mutltiindex_split(self):
+        index = pd.MultiIndex.from_tuples([(1, 1), (2, 1), (1, 2), (2, 2)])
+        expected = pd.Series(data=[1, 2, 3, 4], index=index)
+        js = expected.to_json(orient="split")
+        result = pd.read_json(js, orient="split", typ="series")
+        tm.assert_series_equal(expected, result)
+
     @pytest.mark.parametrize(
         "data",
         [