Allow Set Style by Column

[teschste]

Currently, excelize sets the style on a cell-by-cell basis. If you have a large spreadsheet with a lot of rows, this can be tedious and take progressively longer the more rows need to be set. This can be seen if you try to set a single style on a single empty column, for all 1,048,576 rows. The more columns you attempt this for the longer this takes. While this is an extreme example, setting styles by columns is much simpler and is a common use-case in Excel.

Request that excelize support setting the style by columns (e.g. "A" or "A:A", "A:C", etc). In my own research, this is as simple as setting the style attribute on the col tag for the appropriate column(s).