ENH: Making header_style a property of ExcelFormatter #22758 (#22759)

Author: dannyhyunkim

pandas/io/formats/excel.py

@@ -34,15 +34,6 @@ def __init__(self, row, col, val, style=None, mergestart=None,
         self.mergeend = mergeend
 
 
-header_style = {"font": {"bold": True},
-                "borders": {"top": "thin",
-                            "right": "thin",
-                            "bottom": "thin",
-                            "left": "thin"},
-                "alignment": {"horizontal": "center",
-                              "vertical": "top"}}
-
-
 class CSSToExcelConverter(object):
     """A callable for converting CSS declarations to ExcelWriter styles
 
@@ -389,6 +380,16 @@ def __init__(self, df, na_rep='', float_format=None, cols=None,
         self.merge_cells = merge_cells
         self.inf_rep = inf_rep
 
+    @property
+    def header_style(self):
+        return {"font": {"bold": True},
+                "borders": {"top": "thin",
+                            "right": "thin",
+                            "bottom": "thin",
+                            "left": "thin"},
+                "alignment": {"horizontal": "center",
+                              "vertical": "top"}}
+
     def _format_value(self, val):
         if is_scalar(val) and missing.isna(val):
             val = self.na_rep
@@ -427,24 +428,24 @@ def _format_header_mi(self):
             # Format multi-index as a merged cells.
             for lnum in range(len(level_lengths)):
                 name = columns.names[lnum]
-                yield ExcelCell(lnum, coloffset, name, header_style)
+                yield ExcelCell(lnum, coloffset, name, self.header_style)
 
             for lnum, (spans, levels, labels) in enumerate(zip(
                     level_lengths, columns.levels, columns.labels)):
                 values = levels.take(labels)
                 for i in spans:
                     if spans[i] > 1:
                         yield ExcelCell(lnum, coloffset + i + 1, values[i],
-                                        header_style, lnum,
+                                        self.header_style, lnum,
                                         coloffset + i + spans[i])
                     else:
                         yield ExcelCell(lnum, coloffset + i + 1, values[i],
-                                        header_style)
+                                        self.header_style)
         else:
             # Format in legacy format with dots to indicate levels.
             for i, values in enumerate(zip(*level_strs)):
                 v = ".".join(map(pprint_thing, values))
-                yield ExcelCell(lnum, coloffset + i + 1, v, header_style)
+                yield ExcelCell(lnum, coloffset + i + 1, v, self.header_style)
 
         self.rowcounter = lnum
 
@@ -469,7 +470,7 @@ def _format_header_regular(self):
 
             for colindex, colname in enumerate(colnames):
                 yield ExcelCell(self.rowcounter, colindex + coloffset, colname,
-                                header_style)
+                                self.header_style)
 
     def _format_header(self):
         if isinstance(self.columns, ABCMultiIndex):
@@ -482,7 +483,8 @@ def _format_header(self):
             row = [x if x is not None else ''
                    for x in self.df.index.names] + [''] * len(self.columns)
             if reduce(lambda x, y: x and y, map(lambda x: x != '', row)):
-                gen2 = (ExcelCell(self.rowcounter, colindex, val, header_style)
+                gen2 = (ExcelCell(self.rowcounter, colindex, val,
+                                  self.header_style)
                         for colindex, val in enumerate(row))
                 self.rowcounter += 1
         return itertools.chain(gen, gen2)
@@ -518,15 +520,16 @@ def _format_regular_rows(self):
 
             if index_label and self.header is not False:
                 yield ExcelCell(self.rowcounter - 1, 0, index_label,
-                                header_style)
+                                self.header_style)
 
             # write index_values
             index_values = self.df.index
             if isinstance(self.df.index, ABCPeriodIndex):
                 index_values = self.df.index.to_timestamp()
 
             for idx, idxval in enumerate(index_values):
-                yield ExcelCell(self.rowcounter + idx, 0, idxval, header_style)
+                yield ExcelCell(self.rowcounter + idx, 0, idxval,
+                                self.header_style)
 
             coloffset = 1
         else:
@@ -562,7 +565,7 @@ def _format_hierarchical_rows(self):
 
                 for cidx, name in enumerate(index_labels):
                     yield ExcelCell(self.rowcounter - 1, cidx, name,
-                                    header_style)
+                                    self.header_style)
 
             if self.merge_cells:
                 # Format hierarchical rows as merged cells.
@@ -581,20 +584,20 @@ def _format_hierarchical_rows(self):
                     for i in spans:
                         if spans[i] > 1:
                             yield ExcelCell(self.rowcounter + i, gcolidx,
-                                            values[i], header_style,
+                                            values[i], self.header_style,
                                             self.rowcounter + i + spans[i] - 1,
                                             gcolidx)
                         else:
                             yield ExcelCell(self.rowcounter + i, gcolidx,
-                                            values[i], header_style)
+                                            values[i], self.header_style)
                     gcolidx += 1
 
             else:
                 # Format hierarchical rows with non-merged values.
                 for indexcolvals in zip(*self.df.index):
                     for idx, indexcolval in enumerate(indexcolvals):
                         yield ExcelCell(self.rowcounter + idx, gcolidx,
-                                        indexcolval, header_style)
+                                        indexcolval, self.header_style)
                     gcolidx += 1
 
         for cell in self._generate_body(gcolidx):