From: James Edward Gray II <james@...>
Date: 2006-08-31T02:06:48+09:00
Subject: Re: Parsing CSV file with ruby

On Aug 30, 2006, at 11:01 AM, 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.

I'm assuming you meant CSV (not CVS).  ;)

See if this gets you going:

Firefly:~/Desktop$ cat data.csv
one,1,A
one,2,B
one,3,C
two,1,A
two,2,B
three,1,A
Firefly:~/Desktop$ irb -r csv
 >> rows = CSV.read("data.csv")
=> [["one", "1", "A"], ["one", "2", "B"], ["one", "3", "C"], ["two",  
"1", "A"], ["two", "2", "B"], ["three", "1", "A"]]
 >> groups = rows.map { |row| row.first }.uniq
=> ["one", "two", "three"]
 >> groups.each do |group|
?>   puts group
 >>   rows.select { |row| row.first == group }.each { |row| puts "  # 
{row.inspect}" }
 >> end
one
   ["one", "1", "A"]
   ["one", "2", "B"]
   ["one", "3", "C"]
two
   ["two", "1", "A"]
   ["two", "2", "B"]
three
   ["three", "1", "A"]
=> ["one", "two", "three"]

James Edward Gray II