BUG: Fixes dataFrame to_string(header=False)

doc/source/whatsnew/v2.0.0.rst

@@ -694,7 +694,9 @@ I/O
 - Improved error message in :func:`read_excel` by including the offending sheet name when an exception is raised while reading a file (:issue:`48706`)
 - Bug when a pickling a subset PyArrow-backed data that would serialize the entire data instead of the subset (:issue:`42600`)
 - Bug in :func:`read_csv` for a single-line csv with fewer columns than ``names`` raised :class:`.errors.ParserError` with ``engine="c"`` (:issue:`47566`)
+- Bug in :func:`DataFrame.to_string` with ``header=False`` that printed the index name on the same line as the first row of the data (:issue:`49230`)
 - Fixed memory leak which stemmed from the initialization of the internal JSON module (:issue:`49222`)
+-
 
 Period
 ^^^^^^

pandas/io/formats/printing.py

@@ -51,7 +51,7 @@ def adjoin(space: int, *lists: list[str], **kwargs) -> str:
     maxLen = max(map(len, lists))
     for i, lst in enumerate(lists):
         nl = justfunc(lst, lengths[i], mode="left")
-        nl.extend([" " * lengths[i]] * (maxLen - len(lst)))
+        nl = ([" " * lengths[i]] * (maxLen - len(lst))) + nl
         newLists.append(nl)
     toJoin = zip(*newLists)
     for lines in toJoin:

pandas/tests/io/formats/test_format.py

@@ -1411,25 +1411,25 @@ def test_to_string_no_index(self):
         assert df_s == expected
 
     def test_to_string_line_width_no_index(self):
-        # GH 13998, GH 22505
+        # GH 13998, GH 22505, # GH 49230
         df = DataFrame({"x": [1, 2, 3], "y": [4, 5, 6]})
 
         df_s = df.to_string(line_width=1, index=False)
-        expected = " x  \\\n 1   \n 2   \n 3   \n\n y  \n 4  \n 5  \n 6  "
+        expected = " x   \n 1  \\\n 2   \n 3   \n\n y  \n 4  \n 5  \n 6  "
 
         assert df_s == expected
 
         df = DataFrame({"x": [11, 22, 33], "y": [4, 5, 6]})
 
         df_s = df.to_string(line_width=1, index=False)
-        expected = " x  \\\n11   \n22   \n33   \n\n y  \n 4  \n 5  \n 6  "
+        expected = " x   \n11  \\\n22   \n33   \n\n y  \n 4  \n 5  \n 6  "
 
         assert df_s == expected
 
         df = DataFrame({"x": [11, 22, -33], "y": [4, 5, -6]})
 
         df_s = df.to_string(line_width=1, index=False)
-        expected = "  x  \\\n 11   \n 22   \n-33   \n\n y  \n 4  \n 5  \n-6  "
+        expected = "  x   \n 11  \\\n 22   \n-33   \n\n y  \n 4  \n 5  \n-6  "
 
         assert df_s == expected
 
@@ -1683,6 +1683,20 @@ def test_to_string_line_width(self):
         s = df.to_string(line_width=80)
         assert max(len(line) for line in s.split("\n")) == 80
 
+    def test_to_string_header_false(self):
+        # GH 49230
+        df = DataFrame([1, 2])
+        df.index.name = "a"
+        s = df.to_string(header=False)
+        expected = "a   \n0  1\n1  2"
+        assert s == expected
+
+        df = DataFrame([[1, 2], [3, 4]])
+        df.index.name = "a"
+        s = df.to_string(header=False)
+        expected = "a      \n0  1  2\n1  3  4"
+        assert s == expected
+
     def test_show_dimensions(self):
         df = DataFrame(123, index=range(10, 15), columns=range(30))