Fixed itertuples usage in to_dict

Closes pandas-dev#24940
Closes pandas-dev#24939

Author: TomAugspurger

doc/source/whatsnew/v0.24.1.rst

@@ -29,8 +29,8 @@ Bug Fixes
 
 **Conversion**
 
--
--
+- Bug in :meth:`DataFrame.itertuples` with ``records`` orient raising an AttributeError when the ``DataFrame`` contained more than 255 columns (:issue:`24939`)
+- Bug in :meth:`DataFrame.itertuples` orient converting integer column names to strings prepended with an underscore (:issue:`24940`)
 -
 
 **Indexing**

pandas/core/frame.py

@@ -1296,10 +1296,13 @@ def to_dict(self, orient='dict', into=dict):
             return into_c((k, com.maybe_box_datetimelike(v))
                           for k, v in compat.iteritems(self))
         elif orient.lower().startswith('r'):
+            columns = self.columns.tolist()
+            rows = (dict(zip(columns, row))
+                    for row in self.itertuples(index=False))
             return [
                 into_c((k, com.maybe_box_datetimelike(v))
-                       for k, v in compat.iteritems(row._asdict()))
-                for row in self.itertuples(index=False)]
+                       for k, v in compat.iteritems(row))
+                for row in rows]
         elif orient.lower().startswith('i'):
             if not self.index.is_unique:
                 raise ValueError(

pandas/tests/frame/test_convert_to.py

@@ -488,3 +488,17 @@ def test_to_dict_index_dtypes(self, into, expected):
         result = DataFrame.from_dict(result, orient='index')[cols]
         expected = DataFrame.from_dict(expected, orient='index')[cols]
         tm.assert_frame_equal(result, expected)
+
+    def test_to_dict_numeric_names(self):
+        # https://github.com/pandas-dev/pandas/issues/24940
+        df = DataFrame({str(i): [i] for i in range(5)})
+        result = set(df.to_dict('records')[0].keys())
+        expected = set(df.columns)
+        assert result == expected
+
+    def test_to_dict_wide(self):
+        # https://github.com/pandas-dev/pandas/issues/24939
+        df = DataFrame({('A_%d' % i): [i] for i in range(256)})
+        result = df.to_dict('records')[0]
+        expected = {'A_{:d}'.format(i): i for i in range(256)}
+        assert result == expected