Comments on: Partitioning Sets in Ruby http://www.rubyrailways.com/partitioning-sets-in-ruby/ Experiences with Ruby and Rails, Web2.0 and other development technologies Sat, 31 Jul 2010 08:01:05 +0000 http://wordpress.org/?v=2.7 hourly 1 By: grnch http://www.rubyrailways.com/partitioning-sets-in-ruby/comment-page-1/#comment-40300 grnch Sun, 11 May 2008 14:02:51 +0000 http://www.rubyrailways.com/partitioning-sets-in-ruby/#comment-40300 <p>Come on, you can do better than that :)</p> <p>There is a method Set.classify, related to Set.divide, which gets you closer to your goal:</p> <p>require 'set' input = Set.new open('input.txt').readlines.map{|line| line.chomp.split} groups = input.classify {|e| e.shift} result = groups.map {|k,v| {k => v.to<em>a.flatten.inject(0) {|sum, x| sum+x.to</em>i}}}</p> Come on, you can do better than that :)

There is a method Set.classify, related to Set.divide, which gets you closer to your goal:

require ’set’
input = Set.new open(’input.txt’).readlines.map{|line| line.chomp.split}
groups = input.classify {|e| e.shift}
result = groups.map {|k,v| {k => v.toa.flatten.inject(0) {|sum, x| sum+x.toi}}}

]]> By: peter http://www.rubyrailways.com/partitioning-sets-in-ruby/comment-page-1/#comment-8572 peter Sun, 29 Apr 2007 13:39:05 +0000 http://www.rubyrailways.com/partitioning-sets-in-ruby/#comment-8572 <p>Well, the original idea was to show how Set.divide works... Admiring my just found shiny new hammer, I guess this problem pretty much looked like a big nail :-)</p> <p>Thanks for the solution, Aur.</p> Well, the original idea was to show how Set.divide works… Admiring my just found shiny new hammer, I guess this problem pretty much looked like a big nail :-)

Thanks for the solution, Aur.

]]> By: SonOfLilit http://www.rubyrailways.com/partitioning-sets-in-ruby/comment-page-1/#comment-8567 SonOfLilit Sun, 29 Apr 2007 13:16:21 +0000 http://www.rubyrailways.com/partitioning-sets-in-ruby/#comment-8567 <p>So why complicate it with divide?</p> <p>Why not:</p> <p>#</p> <p>h = {} open('input.txt').each<em>line{|l| h[l[0..0]] += l[2..-1].split(‘ ‘).inject(0) {|c,x| c+=x.to</em>i; c}} } p h.to_a.map{|k,v| {k => v}</p> <p>#</p> <p>?</p> <p>It would also remove the same-line weakness.</p> So why complicate it with divide?

Why not:

#

h = {}
open(’input.txt’).eachline{|l|
h[l[0..0]] +=
l[2..-1].split(‘ ‘).inject(0) {|c,x| c+=x.toi; c}}
}
p h.to_a.map{|k,v| {k => v}

#

?

It would also remove the same-line weakness.

]]> By: peter http://www.rubyrailways.com/partitioning-sets-in-ruby/comment-page-1/#comment-8548 peter Sun, 29 Apr 2007 11:50:35 +0000 http://www.rubyrailways.com/partitioning-sets-in-ruby/#comment-8548 <p>Ben,</p> <p>theoretically that could happen - there is absolutely no guarantee that two rows will be different. Well... it seems even <i>divide</i> is not perfect (it could do the partitioning into a Hash, where the value set would be the number of occurrences of the sets or something) - or maybe this is possible somehow? Going to check it...</p> Ben,

theoretically that could happen - there is absolutely no guarantee that two rows will be different.
Well… it seems even divide is not perfect (it could do the partitioning into a Hash, where the value set would be the number of occurrences of the sets or something) - or maybe this is possible somehow?
Going to check it…

]]> By: Ben http://www.rubyrailways.com/partitioning-sets-in-ruby/comment-page-1/#comment-8160 Ben Fri, 27 Apr 2007 18:18:58 +0000 http://www.rubyrailways.com/partitioning-sets-in-ruby/#comment-8160 <p>What happens if you have 2 lines with the same numbers - or does that never happen?</p> What happens if you have 2 lines with the same numbers - or does that never happen?

]]>