From: James Edward Gray II <james@...>
Date: 2006-12-19T07:21:24+09:00
Subject: Re: Output unique values in CSV columns to a text file

On Dec 18, 2006, at 4:04 PM, Drew Olson wrote:

> What I want to do is read in a CSV file and produce an output which
> lists the unique values from each column in the following format:
>
> Column: ColHeader1
>    UniqueVal1
>    UniqueVal2
> Column: ColHeader2
>    UniqueVal1
>    UniqueVal2
> ...

Well, if it all fits in memory it's super easy using FCSV's Tables:

#!/usr/bin/env ruby -w

require "rubygems"
require "faster_csv"

table = FCSV.parse(DATA.read, :headers => true)
table.by_col!.each do |header, col|
   puts "#{header}:"
   puts "  #{col.uniq.join(', ')}"
end

__END__
nums,letters
1,a
2,b
2,b
3,c
3,c
3,c

James Edward Gray II