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ruby – Permutation between elements of an array

I’m coding a plugin in Google Sketchup with ruby and I faced a real problem while trying to permute different elements in arrays that are present in an another array, all this depending on a user combination.

I have an array of arrays like:

[["a, "b", c"], ["lol1", "lol2", lol3"], ["so1", "so2", "so3"]]

For a combination like:

[1, 2, 3]

The output should still same:

[["a", "b", "c"], ["lol1", "lol2", "lol3"], ["so1", "so2", "so3"]]

But for a combination like:

[2, 1, 3]

The output should be:

[["b", "a", "c"], ["lol2", "lol1", "lol3"], ["so2", "so1", "so3"]]

But for a combination like:

[3, 2, 1]

The output should be:

[["c", "b", a"], ["lol3", "lol2", "lol1"], ["so3", "so2", "so1"]]

Answer 1

ar = [["a, b, c"], ["lol1, lol2, lol3"], ["so1, so2, so3"]]
p maybe_this = ar.map{|sub_ar| sub_ar.first.split(', ')}
#[["a", "b", "c"], ["lol1", "lol2", "lol3"], ["so1", "so2", "so3"]]
idx = [2,1,3]
#indexing of an array is zero-based
p idx.map!{|i| i-1} #[1,0,2]
p res = maybe_this.map{|sub_ar| sub_ar.values_at(*idx)}
#[["b", "a", "c"], ["lol2", "lol1", "lol3"], ["so2", "so1", "so3"]]

The short story: the values_at method takes multiple arguments; *idx splats an array into multiple arguments.