From: Josh Cheek <josh.cheek@...>
Date: 2010-03-29T23:14:41+09:00
Subject: Re: Easy task, Sum array element... Why doesn't it work?

--000e0cd1aa3e4203b70482f12286
Content-Type: text/plain; charset=ISO-8859-1

On Mon, Mar 29, 2010 at 4:26 AM, Walle Wallen <walle.sthlm@gmail.com> wrote:

> I have done it many times before, but this time I can't get it too work.
> I'm starting to get a bit frustrating.
> So, I'm trying to sum all elements from the second element in a Array
> using inject. The problem is that inject returns nil every time. What am
> I doing wrong?
>
> parameters.each {|element| print element + ","} --> ?faq,using,rtorrent
> parameters.each {|element| print element.class.to_s + ","} -->
> String,String,String
> parameters.class --> Array
>
> Doesn't work.
> (parameters[1]..parameters[-1]).inject {|result, element| result +
> element} --> nil
> Neither does.
> (parameters[1]..parameters[-1]).to_a.inject {|result, element| result +
> element} --> nil
>
> //Walle
> --
> Posted via http://www.ruby-forum.com/.
>
>
Rails has this by default:
http://api.rubyonrails.org/classes/Enumerable.html#M002571

module Enumerable
  def sum(identity = 0, &block)
    return identity unless size > 0

    if block_given?
      map(&block).sum
    else
      inject { |sum, element| sum + element }
    end
  end
end

['a','b','c'].sum              # => "abc"
[1,2,3].sum                    # => 6
[[0],['0'],[:'0'],[/0/]].sum   # => [0, "0", :"0", /0/]
[].sum(/abc/)                  # => /abc/
[1,2,3].sum(/abc/)             # => 6
['a','b','c'].sum(&:upcase)    # => "ABC"

That last one is 1.9 only (or another monkey patch ;P )

--000e0cd1aa3e4203b70482f12286--