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.