Pandas ExcelWriter set_column fails to format numbers after DataFrame.to_excel used
I have tried the example code found on the xlsxwriter webpage at http://xlsxwriter.readthedocs.org/en/latest/example_pandas_column_formats.html

However it does not format the columns as expected - they simply appear unformatted (no numeric rounding, percentages.)

It seems that calling set_column is being ignored. Is this because perhaps not to_excel() is doing some formatting itself which can't be overwritten?
