Merge pull request #11233 from taeold/bugfix/multiindex-frame-to-latex-bug

BUG: to_latex() output broken when the index has a name (GH10660)

Author: jreback

doc/source/whatsnew/v0.17.1.txt

@@ -42,3 +42,4 @@ Performance Improvements
 
 Bug Fixes
 ~~~~~~~~~
+Bug in ``.to_latex()`` output broken when the index has a name (:issue: `10660`)

pandas/core/format.py

@@ -636,11 +636,13 @@ def get_col_type(dtype):
         if self.index and isinstance(self.frame.index, MultiIndex):
             clevels = self.frame.columns.nlevels
             strcols.pop(0)
-            name = any(self.frame.columns.names)
+            name = any(self.frame.index.names)
             for i, lev in enumerate(self.frame.index.levels):
-                lev2 = lev.format(name=name)
+                lev2 = lev.format()
                 blank = ' ' * len(lev2[0])
                 lev3 = [blank] * clevels
+                if name:
+                    lev3.append(lev.name)
                 for level_idx, group in itertools.groupby(
                         self.frame.index.labels[i]):
                     count = len(list(group))
@@ -667,6 +669,8 @@ def write(buf, frame, column_format, strcols, longtable=False):
                 buf.write('\\toprule\n')
 
             nlevels = frame.columns.nlevels
+            if any(frame.index.names):
+                nlevels += 1
             for i, row in enumerate(zip(*strcols)):
                 if i == nlevels:
                     buf.write('\\midrule\n')  # End of header

pandas/tests/test_format.py

@@ -2645,6 +2645,50 @@ def test_to_latex_multiindex(self):
 c3 & 0 &  0 &  1 &  2 &  3 \\
 \bottomrule
 \end{tabular}
+"""
+        self.assertEqual(result, expected)
+
+        # GH 10660
+        df = pd.DataFrame({'a':[0,0,1,1], 'b':list('abab'), 'c':[1,2,3,4]})
+        result = df.set_index(['a', 'b']).to_latex()
+        expected = r"""\begin{tabular}{llr}
+\toprule
+  &   &  c \\
+a & b &    \\
+\midrule
+0 & a &  1 \\
+  & b &  2 \\
+1 & a &  3 \\
+  & b &  4 \\
+\bottomrule
+\end{tabular}
+"""
+        self.assertEqual(result, expected)
+
+        result = df.groupby('a').describe().to_latex()
+        expected = r"""\begin{tabular}{llr}
+\toprule
+  &       &         c \\
+a & {} &           \\
+\midrule
+0 & count &  2.000000 \\
+  & mean &  1.500000 \\
+  & std &  0.707107 \\
+  & min &  1.000000 \\
+  & 25\% &  1.250000 \\
+  & 50\% &  1.500000 \\
+  & 75\% &  1.750000 \\
+  & max &  2.000000 \\
+1 & count &  2.000000 \\
+  & mean &  3.500000 \\
+  & std &  0.707107 \\
+  & min &  3.000000 \\
+  & 25\% &  3.250000 \\
+  & 50\% &  3.500000 \\
+  & 75\% &  3.750000 \\
+  & max &  4.000000 \\
+\bottomrule
+\end{tabular}
 """
         self.assertEqual(result, expected)