FastExcel / libxlsxwriter: Cannot use space as thousands separator in number formats

[durcak]

Description

When trying to use a custom number format with a space as the thousands separator, e.g.:

workbook.add_format(num_format: '# ##0.00 "€"')

FastExcel / libxlsxwriter escapes the space and other special characters, resulting in a format like #\ ##0.00\ €. Excel then displays large numbers incorrectly, e.g., 1200300.99 becomes 1200 300.99.

Steps to reproduce

1. Create a FastExcel workbook.
2. Add a worksheet and a number format like # ##0.00 "€".
3. Write a number larger than 999,999 with write_number.
4. Open the generated Excel file in Excel.

Expected behavior

The number should display with a proper space as thousands separator, e.g., 1 200 300.99 €.

Actual behavior

The number is split incorrectly because the space is escaped (#\ ##0.00\ €) and interpreted literally by Excel.

Notes

• Using commas (,) or dots (.) works correctly, e.g., #,##0.00 "€".
• Using a space as thousands separator is not supported due to internal escaping in libxlsxwriter.

Environment

• FastExcel version: 0.5.0

Request

Please consider supporting non-escaped spaces as thousands separators, or provide a recommended workaround for properly displaying numbers with spaces.

[Vaurien]

Try
workbook.add_format(num_format: "# ##0.00 €")