From: Paul Lutus <nospam@...>
Date: 2006-08-31T01:55:29+09:00
Subject: Re: Parsing CSV file with ruby

Drew Olson wrote:

> Let me be more specific: essentially I want to find the groups of rows
> that share an element. Let's say each row in my CVS doc has 3 elements.
> I want to iterate across every group of rows that share the same value
> for the first element. Hope this makes sense.
> 

#!/usr/bin/ruby -w

row_hash = {}

File.open("data.txt").each { |record|
   fields = record.split(",")
   row_hash[fields.first] = [] unless row_hash[fields.first]
   row_hash[fields.first] << record
}

row_hash.keys.sort.each { |key|
   puts "Group: #{key}"
   row_hash[key].each { |record|
      puts "\t#{record}"
   }
}

data.txt:

a,this,is,one,record
a,this,is,another,record
b,this,is,one,record
b,this,is,another,record
c,this,is,one,record
c,this,is,another,record

output:

Group: a
        a,this,is,one,record
        a,this,is,another,record
Group: b
        b,this,is,one,record
        b,this,is,another,record
Group: c
        c,this,is,one,record
        c,this,is,another,record

-- 
Paul Lutus
http://www.arachnoid.com