From: Drew Olson <olsonas@...>
Date: 2007-03-23T23:04:54+09:00
Subject: Re: count distinct values in csv

Christian Schulz wrote:
> Hi,
> 
> i'm new to ruby.
> How  could i read a tab-delimted textfile  with two columns + header
> row
> and count the distinct values from the 2.column?

Christian -

Strangely enough, I wrote a blog post about this very topic:

http://drewolson.wordpress.com/2007/03/13/csv-manipulation-w-ruby/

Here's the code linked to by the blog post:

require 'faster_csv'

unique_count = {}

FCSV.foreach("myfile.csv", :headers => true) do |row|
  unique_count[row[1]] ||= 0
  unique_count[row[1]] += 1
end

unique_count.each do |val,count|
  puts "#{val} appreas #{count} time(s)"
end



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