From: "Eustáquio 'TaQ' Rangel" <eustaquiorangel@...>
Date: 2008-03-26T23:32:56+09:00
Subject: Re: The inject function

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| I want to add together numbers in an array with the inject command. I
| want only the even numbers using only inject.
| So, something like [1,2,3,4].inject.....but don't know what to do so
| help!

Use select before inject:

[1,2,3,4,5,6].select {|i| i%2==0}.inject {|m,v| m+v}

You could use a test to sum the number only when it's even on inject, but

[1,2,3,4,5,6].inject {|m,v| m + (v%2==0?v:0) }

results to 13, because seems that the value of m is automatically the first
element of the array. On this case, you can tell it to start with 0:

[1,2,3,4,5,6].inject(0) {|m,v| m + (v%2==0?v:0) }

| Second, I need to reverse an array using only the inject command. So,
| something like above with the result [4,3,2,1]

Why don't you use reverse?

[1,2,3,4,5,6].reverse

Regards,
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