Merge pull request #5589 from y-p/PR_fix_slow_truncated_large_repr_html_5588

BUG: to_html doesn't slice index to max_rows before formatting

Author: y-p

pandas/core/format.py

@@ -819,14 +819,14 @@ def _write_body(self, indent):
 
     def _write_regular_rows(self, fmt_values, indent, truncated):
         ncols = min(len(self.columns), self.max_cols)
-
+        nrows = min(len(self.frame), self.max_rows)
         fmt = self.fmt._get_formatter('__index__')
         if fmt is not None:
-            index_values = self.frame.index.map(fmt)
+            index_values = self.frame.index[:nrows].map(fmt)
         else:
-            index_values = self.frame.index.format()
+            index_values = self.frame.index[:nrows].format()
 
-        for i in range(min(len(self.frame), self.max_rows)):
+        for i in range(nrows):
             row = []
             row.append(index_values[i])
             row.extend(fmt_values[j][i] for j in range(ncols))

vb_suite/frame_methods.py

@@ -145,6 +145,20 @@ def f(x):
 frame_to_string_floats = Benchmark('df.to_string()', setup,
                                    start_date=datetime(2010, 6, 1))
 
+#----------------------------------------------------------------------
+# to_html
+
+setup = common_setup + """
+nrows=500
+df = DataFrame(randn(nrows, 10))
+df[0]=period_range("2000","2010",nrows)
+df[1]=range(nrows)
+
+"""
+
+frame_to_html_mixed = Benchmark('df.to_html()', setup,
+                                   start_date=datetime(2010, 6, 1))
+
 # insert many columns
 
 setup = common_setup + """