ruby array element grouping

Question

here is the problem

I have an array:

a = [1, 2, 3, 4]

and want to get:

b = [[1, 2, 3], [1, 3, 4], [1, 2, 4], [2, 3, 4]]

what is the best way? thanks!

what have you tried? and what would be the expected output there? do you want all 7 element groups? all 3 element groups? Ask the question better and you'll get answers better than my snark. — Alexander Corwin
– Alexander Corwin, Commented Mar 12, 2012 at 20:10

vdeantoni · Accepted Answer · 2012-03-12 20:24:55Z

3

You are looking for all unique sets of 3 elements out of a set of 4.

Use Array#combination method:

a = [1, 2, 3, 4]
b = a.combination(3).to_a

output:

=> [[1, 2, 3], [1, 2, 4], [1, 3, 4], [2, 3, 4]]

More info:

answered Mar 12, 2012 at 20:11

vdeantoni

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Comments

Deradon · Accepted Answer · 2012-03-12 20:12:28Z

0

Here would be my first implementation. (But performance suckz i guess)

array = [1,2,3,4]
b = []
array.each{|e| c = array.clone; c.delete(e); b << c}
# b.sort!

answered Mar 12, 2012 at 20:12

Deradon

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