CODEWITHSUNDEEP
arraysruby
con
con

Reputation: 6093

Using one array to index another in Ruby

I am trying to learn Ruby, and I'm wondering how an array can be used to index another array, for example,

in Perl this is: my @x = @y[@ro], where all three variables are just generic arrays.

how can I accomplish the same thing in Ruby?

Upvotes: 1

Views: 66

Answers (1)

mu is too short
mu is too short

Reputation: 434665

If I remember my Perl correctly, given:

my @ro = ('a', 'b', 'c', 'd', 'e');
my @y  = (1, 3);

Then @ro[@y] would be ('b', 'd') so the notation is just a short form for extracting all the elements of the array @ro at the indexes in @y.

In Ruby, I'd use Array#values_at and a splat thusly:

ro = %w[a b c d e]
y  = [1, 3]
x  = ro.values_at(*y)

The *y splat unwraps the array and gives you its elements so ro.values_at(*y) is equivalent to ro.values_at(1, 3) in this case.

Upvotes: 5

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