reverted to methodology of commit 911a491 (pandas-dev#25436)

Author: jeschwar

pandas/io/formats/latex.py

@@ -102,7 +102,10 @@ def pad_empties(x):
             raise AssertionError('column_format must be str or unicode, '
                                  'not {typ}'.format(typ=type(column_format)))
 
-        buf.write(self._build_latex_begin_env(column_format))
+        if self.longtable:
+            self._write_longtable_begin(buf, column_format)
+        else:
+            self._write_tabular_begin(buf, column_format)
 
         buf.write('\\toprule\n')
 
@@ -155,7 +158,10 @@ def pad_empties(x):
             if self.multirow and i < len(strrows) - 1:
                 self._print_cline(buf, i, len(strcols))
 
-        buf.write(self._build_latex_end_env())
+        if self.longtable:
+            self._write_longtable_end(buf)
+        else:
+            self._write_tabular_end(buf)
 
     def _format_multicolumn(self, row, ilevels):
         r"""
@@ -232,87 +238,73 @@ def _print_cline(self, buf, i, icol):
         # remove entries that have been written to buffer
         self.clinebuf = [x for x in self.clinebuf if x[0] != i]
 
-    def _build_latex_begin_env(self, column_format):
+    def _write_tabular_begin(self, buf, column_format):
         """
-        Write the beginning of the latex environment.
-
-        This can be a tabular environment or nested table/tabular environments
-        including caption/label depending on the arguments passed to
-        `LatexFormatter.__init__()`.
-
-        Returns
-        -------
-        string
-            to be written to `buf`
+        write the beginning of a tabular environment or
+        nested table/tabular environments including caption and label
         """
-        str_ = ''
-        if self.longtable:
-            str_ += '\\begin{{longtable}}{{{fmt}}}\n'.format(fmt=column_format)
-
-            if self.caption is None and self.label is None:
-                pass
-            else:
-                if self.caption is None:
-                    pass
-                else:
-                    str_ += '\\caption{{{}}}'.format(self.caption)
-
-                if self.label is None:
-                    pass
-                else:
-                    str_ += '\\label{{{}}}'.format(self.label)
-
-                # a double-backslash is required at the end of the line
-                # as discussed here:
-                # https://tex.stackexchange.com/questions/219138
-                str_ += '\\\\\n'
+        if self.caption is None and self.label is None:
+            # then write output only in a tabular environment
+            pass
         else:
-            if self.caption is None and self.label is None:
-                # then write output only in a tabular environment
-                pass
+            # then write output in a nested table/tabular environment
+            if self.caption is None:
+                caption_ = ''
             else:
-                # then write output in a nested table/tabular environment
-                if self.caption is None:
-                    caption_ = ''
-                else:
-                    caption_ = '\n\\caption{{{}}}'.format(self.caption)
-
-                if self.label is None:
-                    label_ = ''
-                else:
-                    label_ = '\n\\label{{{}}}'.format(self.label)
+                caption_ = '\n\\caption{{{}}}'.format(self.caption)
 
-                str_ += '\\begin{{table}}\n\\centering{}{}\n'.format(
-                    caption_,
-                    label_
-                )
+            if self.label is None:
+                label_ = ''
+            else:
+                label_ = '\n\\label{{{}}}'.format(self.label)
 
-            str_ += '\\begin{{tabular}}{{{fmt}}}\n'.format(fmt=column_format)
+            buf.write('\\begin{{table}}\n\\centering{}{}\n'.format(
+                caption_,
+                label_
+            ))
 
-        return str_
+        buf.write('\\begin{{tabular}}{{{fmt}}}\n'.format(fmt=column_format))
 
-    def _build_latex_end_env(self):
+    def _write_longtable_begin(self, buf, column_format):
         """
-        Write the end of the latex environment.
-
-        This can be a tabular environment or nested table/tabular environments
-        depending on the arguments passed to `LatexFormatter.__init__()`.
-
-        Returns
-        -------
-        string
-            to be written to `buf`
+        write the beginning of a longtable environment including caption and
+        label if provided by user
         """
-        str_ = ''
+        buf.write('\\begin{{longtable}}{{{fmt}}}\n'.format(fmt=column_format))
 
-        if self.longtable:
-            str_ += '\\end{longtable}\n'
+        if self.caption is None and self.label is None:
+            pass
         else:
-            str_ += '\\bottomrule\n'
-            str_ += '\\end{tabular}\n'
-            if self.caption is None and self.label is None:
+            if self.caption is None:
                 pass
             else:
-                str_ += '\\end{table}\n'
+                buf.write('\\caption{{{}}}'.format(self.caption))
+
+            if self.label is None:
+                pass
+            else:
+                buf.write('\\label{{{}}}'.format(self.label))
+
+            # a double-backslash is required at the end of the line
+            # as discussed here:
+            # https://tex.stackexchange.com/questions/219138
+            buf.write('\\\\\n')
 
-        return str_
+    def _write_tabular_end(self, buf):
+        """
+        write the end of a tabular environment or nested table/tabular
+        environment
+        """
+        buf.write('\\bottomrule\n')
+        buf.write('\\end{tabular}\n')
+        if self.caption is None and self.label is None:
+            pass
+        else:
+            buf.write('\\end{table}\n')
+
+    @staticmethod
+    def _write_longtable_end(buf):
+        """
+        write the end of a longtable environment
+        """
+        buf.write('\\end{longtable}\n')