How to find each sum of array in Ruby

Question

I am trying to find sum of each array.

(1..9).to_a.combination(3).to_a.each{ |item| item.inject{:+}}

But my code gives the followings.

[[1, 2, 3], [1, 2, 4], [1, 2, 5], [1, 2, 6], [1, 2, 7], [1, 2, 8], [1, 2, 9], 
[1, 3, 4], [1, 3, 5], [1, 3, 6], [1, 3, 7], [1, 3, 8], ...

What I am expecting is something like this.

[6, 7, 8, 9,...]

How can I find sum of each array?

if you are using rails then you can use sum method like (1..9).to_a.combination(3).map{|a| a.sum(0)} — Alok Anand
– Alok Anand, Commented Apr 18, 2014 at 13:24

Jozsef NYITRAI · Accepted Answer · 2014-04-18 13:18:03Z

10

You are very close, a little change on your code may help:

(1..9).to_a.combination(3).map { |a| a.inject(:+) }

answered Apr 18, 2014 at 13:18

Jozsef NYITRAI

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Comments

mdesantis · Accepted Answer · 2014-04-18 13:17:20Z

6

(1..9).to_a.combination(3).to_a.map { |item| item.inject(:+) }

answered Apr 18, 2014 at 13:17

mdesantis

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shin · Accepted Answer · 2014-04-18 23:35:36Z

0

I found another way with #reduce.

(1..9).to_a.combination(3).map { |item| item.reduce(:+) }

answered Apr 18, 2014 at 23:35

shin

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reduce is an alias for inject, but I prefer it in this case.