Gavin Kistner
6/7/2007 6:10:00 PM
From: bbiker [mailto:renard@nc.rr.com]
Sent: Thursday, June 07, 2007 12:00 PM
> I am not exactly sure what the OP was trying to do .. except that it
> has to do with Columns in Excel. It does seems to me to be fairly
> complicated. If this off topic, please excuse.
[snip]
> # method to convert from numeric column to alpha col
> # accepts numeric column 1 through 256
> # returns alpha column A through IV
> # returns empty string on invalid input
> def n2a_col(num_col)
>
> # verify that it in the range of 1 to 255
> return nil if num_col < 1 || num_col > 256
>
> mostSD = num_col / 26 # SD = Significant Digit
> leastSD = num_col % 26
>
> if leastSD == 0
> mostSD -= 1
> leastSD = 26
> end
>
> leastSA = ('A'[0] + leastSD - 1 ).chr
> mostSA = mostSD > 0 ? ('A'[0] + mostSD - 1).chr : ''
>
> mostSA + leastSA
> end
Not as efficient, but simpler:
def n2a_col( num_col )
if (1..255).include?( num_col )
a = 'A'
( num_col-1 ).times{ a = a.succ }
a
end
end
[ 0, 1, 2, 26, 27, 250, 255, 256 ].each{ |n|
puts "%3d => %s" % [ n, n2a_col( n ).inspect ]
}
#=> 0 => nil
#=> 1 => "A"
#=> 2 => "B"
#=> 26 => "Z"
#=> 27 => "AA"
#=> 250 => "IP"
#=> 255 => "IU"
#=> 256 => nil