Generate a sequence of column labels to match Excel's
naming
Usage
excelCols(n)
Arguments
n
an integer that indicates how many named columns
the user wishes to obtain
Value
a vector of strings of length n
Details
Excel columns are labeled with letters (e.g., A, B, C,
... AA, AB, AC, etc). Given an integer (n), this function
will return labels starting from A until the nth column.
See examples.