From: Robert Klemme <shortcutter@...>
Date: 2011-03-23T00:08:45+09:00
Subject: Re: summing values in a hash?

On Tue, Mar 22, 2011 at 3:13 PM, Robert Dober <robert.dober@gmail.com> wrote:
> On Tue, Mar 22, 2011 at 2:05 PM, Robert Klemme
> <shortcutter@googlemail.com> wrote:
>> On Tue, Mar 22, 2011 at 2:01 PM, Adam Prescott <mentionuse@gmail.com> wrote:
>>> On Tue, Mar 22, 2011 at 12:57 PM, Jen <jen.bottom@gmail.com> wrote:
>>>
>>>> Is there an inbuilt method to sum all values in a hash and return the
>>>> result?
>>>>
>>>> I.E something like puts hash[values].sum
>>>>
>>>
>>> You could try
>>>
>>> hash.values.inject { |a, b| a + b }
>>>
>>> Alternatively, you have the shorter form, inject(&:+) or inject(:+)
>>> depending on your version of Ruby. 1.8.7 and higher should support all
>>> three.
>>
>> You should rather use a different idiom because your solution breaks
>> for empty Hash:
>>
>> irb(main):001:0> {}.values.inject {|a,b|a+b}
>> => nil
>> irb(main):002:0> {}.values.inject(0) {|a,b|a+b}
>> => 0
> slightly better, because working ;)
>    .inject(0){|a,(_,b)|a+b}

What do you mean by that?  Where was my solution not working?

robert


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