Preserving styles using python's xlrd,xlwt, and xlutils.copy

Question

There are two parts to this.

First, you must enable the reading of formatting info when opening the source workbook. The copy operation will then copy the formatting over.

import xlrd
import xlutils.copy

inBook = xlrd.open_workbook('input.xls', formatting_info=True)
outBook = xlutils.copy.copy(inBook)

Secondly, you must deal with the fact that changing a cell value resets the formatting of that cell.

This is less pretty; I use the following hack where I manually copy the formatting index (xf_idx) over:

def _getOutCell(outSheet, colIndex, rowIndex):
    """ HACK: Extract the internal xlwt cell representation. """
    row = outSheet._Worksheet__rows.get(rowIndex)
    if not row: return None

    cell = row._Row__cells.get(colIndex)
    return cell

def setOutCell(outSheet, col, row, value):
    """ Change cell value without changing formatting. """
    # HACK to retain cell style.
    previousCell = _getOutCell(outSheet, col, row)
    # END HACK, PART I

    outSheet.write(row, col, value)

    # HACK, PART II
    if previousCell:
        newCell = _getOutCell(outSheet, col, row)
        if newCell:
            newCell.xf_idx = previousCell.xf_idx
    # END HACK

outSheet = outBook.get_sheet(0)
setOutCell(outSheet, 5, 5, 'Test')
outBook.save('output.xls')

This preserves almost all formatting. Cell comments are not copied, though.

Here's an example of usage of code that I'll propose as a patch against xlutils 1.4.1

# coding: ascii

import xlrd, xlwt

# Demonstration of copy2 patch for xlutils 1.4.1

# Context:
# xlutils.copy.copy(xlrd_workbook) -> xlwt_workbook
# copy2(xlrd_workbook) -> (xlwt_workbook, style_list)
# style_list is a conversion of xlrd_workbook.xf_list to xlwt-compatible styles

# Step 1: Create an input file for the demo
def create_input_file():
    wtbook = xlwt.Workbook()
    wtsheet = wtbook.add_sheet(u'First')
    colours = 'white black red green blue pink turquoise yellow'.split()
    fancy_styles = [xlwt.easyxf(
        'font: name Times New Roman, italic on;'
        'pattern: pattern solid, fore_colour %s;'
         % colour) for colour in colours]
    for rowx in xrange(8):
        wtsheet.write(rowx, 0, rowx)
        wtsheet.write(rowx, 1, colours[rowx], fancy_styles[rowx])
    wtbook.save('demo_copy2_in.xls')

# Step 2: Copy the file, changing data content
# ('pink' -> 'MAGENTA', 'turquoise' -> 'CYAN')
# without changing the formatting

from xlutils.filter import process,XLRDReader,XLWTWriter

# Patch: add this function to the end of xlutils/copy.py
def copy2(wb):
    w = XLWTWriter()
    process(
        XLRDReader(wb,'unknown.xls'),
        w
        )
    return w.output[0][1], w.style_list

def update_content():
    rdbook = xlrd.open_workbook('demo_copy2_in.xls', formatting_info=True)
    sheetx = 0
    rdsheet = rdbook.sheet_by_index(sheetx)
    wtbook, style_list = copy2(rdbook)
    wtsheet = wtbook.get_sheet(sheetx)
    fixups = [(5, 1, 'MAGENTA'), (6, 1, 'CYAN')]
    for rowx, colx, value in fixups:
        xf_index = rdsheet.cell_xf_index(rowx, colx)
        wtsheet.write(rowx, colx, value, style_list[xf_index])
    wtbook.save('demo_copy2_out.xls')

create_input_file()
update_content()