Created
May 25, 2018 07:09
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| module ExcelColumnsConverions | |
| # convert the column name ("A", "ACB", ...) to an number (1-based) | |
| def excel_col_number(str) | |
| offset = 'A'.ord - 1 | |
| str.chars.inject(0){ |x,c| x*26 + c.ord - offset }.to_i | |
| end | |
| # convert the column number to a string ("A", "ACB", ...) | |
| def excel_col_string(number) | |
| # limit: 16.384 | |
| raise "Number must be less than or equal to 16384" if number>16384 | |
| n = number-1 | |
| d3 = (n-26*27)/(26*26) | |
| d3 = d3<0 ? -1 : d3 | |
| d2 = (n-26)/26 | |
| d2 = d2<0 ? -1 : d2%26 | |
| d1 = n%26 | |
| arr = ("A".."Z").to_a | |
| arr_w_space = [""]+arr | |
| [arr_w_space[d3+1], arr_w_space[d2+1], arr[d1]].join | |
| end | |
| def check(max) | |
| 1.upto(max) do |n| | |
| s = excel_col_string(n) | |
| nn = excel_col_index(s) | |
| puts "#{n} -> '#{s}' -> #{nn}" if n!=nn | |
| end | |
| end | |
| end |
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excel_col_numberfunction copied from https://stackoverflow.com/questions/26771129/convert-excel-column-letter-to-integer-in-ruby