From: redstun <redstun@...>
Date: 2011-01-24T15:06:25+09:00
Subject: Re: Enumerable.inject_with_index?

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Cool! thanks!

I was working with array, so I can write
[3, 4, 5].each_with_index.inject(0) { |sum, (value, index)| sum + value *
index } #=> 14

OR
ary = [3, 4, 5]
ary.each_index.inject(0) { |sum, index| sum + ary[index] * index } #=> 14

works like a charm :-)

botp, Thank you very much!

BTW, one more finding is that,
puts([3, 4, 5].each_with_index.inject(0) do |sum, (value, index)| sum +
value * index end)
puts([3, 4, 5].each_with_index.inject(0) { |sum, (value, index)| sum + value
* index })
puts [3, 4, 5].each_with_index.inject(0) { |sum, (value, index)| sum + value
* index }
puts [3, 4, 5].each_with_index.inject(0) do |sum, (value, index)| sum +
value * index end

all works but the last one, it reports TypeError: 0 is not a symbol,
actually caused by the block being passed to puts instead of inject, then
without a block, inject expect a symbol as argument. hum, just a note to
myself.

On Sun, Jan 23, 2011 at 11:10 PM, botp <botpena@gmail.com> wrote:

> On Sun, Jan 23, 2011 at 11:00 PM, botp <botpena@gmail.com> wrote:
> >  (0..5).each.with_index.inject(0){|sum,(i,j)|  sum+j}
> >  #=> 15
> >  (0..5).each.with_index.inject(0){|sum,(i,j)|  sum+i*j}
> >  #=> 55
>
> sorry if that wasn't so clear. again,
>
>  (3..5).each.with_index.inject(0){|sum,(value,index)|  sum+value}
>  #=> 12
>
>  (3..5).each.with_index.inject(0){|sum,(value,index)|  sum+index}
>  #=> 3
>
>  (3..5).each.with_index.inject(0){|sum,(value,index)|  sum+index*value}
>  #=> 14
>
> kind regards -botp
>
>

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