Extracting multiple entries of a Ruby array

Question

Let's say I have an array

arry = ["a","b","c","d","e","f","g"]

and I want to get the fourth, second, and seventh element of that array.

Let's say some other function determined which are the needed values and passed me backan array of indices like [3, 1, 6]. In most languages I could write this

array[3,1,6] #=> ["d","b","g"] (or "dbg"?)

or

array[3 1 6] #=> ["d","b","g"]

But that won't work in Ruby, of course. Is there a simple way to do this in Ruby? The cleanest I can find is something like:

[3,1,6].map { |i| array[i] }

I really tried to find a duplicate to this question since it seems so basic, but I just couldn't.

This is remarkably easy to do in most languages, so I'm almost assuming I'm just overlooking the remarkably obvious.

Huluk · Accepted Answer · 2014-02-02 23:24:48Z

6

array.values_at(3,1,6) #=> ["d","b","g"]

answered Feb 2, 2014 at 23:24

Huluk

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1 Comment

John Rhoades Over a year ago

Dang it. Knew it was something simple. Not as simple as just being a function of [] like I'd assumed, but this is just what I was looking for. Thanks!

Borodin · Accepted Answer · 2014-02-03 02:39:29Z

0

If your other function returns an array then you must flatten it before you can pass it as parameters to values_at. Like this

arry = ["a","b","c","d","e","f","g"]

def indices
  [1,3,6]
end

puts arry.values_at(*indices)

output

b
d
g

answered Feb 3, 2014 at 2:39

Borodin

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