BUG-25061 fix printing indices with NaNs

Author: JustinZhengBC

doc/source/whatsnew/v0.24.2.rst

@@ -52,7 +52,7 @@ Bug Fixes
 **I/O**
 
 - Bug in reading a HDF5 table-format ``DataFrame`` created in Python 2, in Python 3 (:issue:`24925`)
--
+- Bug where float indexes could have misaligned values when printing (:issue:`25061`)
 -
 
 **Categorical**

pandas/io/formats/format.py

@@ -1060,6 +1060,11 @@ def get_result_as_array(self):
         def format_values_with(float_format):
             formatter = self._value_formatter(float_format, threshold)
 
+            # default formatter leaves a space to the left when formatting
+            # floats, must be consistent for left-justifying NaNs (GH #25061)
+            if self.justify == 'left':
+                self.na_rep = ' ' + self.na_rep
+
             # separate the wheat from the chaff
             values = self.values
             mask = isna(values)

pandas/tests/series/test_repr.py

@@ -198,6 +198,13 @@ def test_latex_repr(self):
 
         assert s._repr_latex_() is None
 
+    def test_categorical_index_repr_in_frame_with_nan(self):
+        i = Index([1, np.nan])
+        s = Series([1, 2], index=i)
+        exp = """1.0    1\nNaN    2\ndtype: int64"""
+
+        assert repr(s) == exp
+
 
 class TestCategoricalRepr(object):