Specifying the dataFormat
argument allows you to format the
cell. For example, "#,##0.00" corresponds to using a comma separator
for powers of 1000 with two decimal places, "m/d/yyyy" can be used to
format dates and is the equivalent of R's MM/DD/YYYY format. To
format datetimes use "m/d/yyyy h:mm:ss;@". To show negative values in
red within parantheses with two decimals and commas after power of
1000 use "#,##0.00_);[Red](#,##0.00)". I am not aware of an official
way to discover these strings. I find them out by recording a macro
that formats a specific cell and then checking out the resulting VBA
code. From there you can read the dataFormat
code.