How to get multiple values from array based on indices in Ruby?

Question

We have an array, say:

my_arr = [121, 23, 46, 91, 38, 140]

Also we have the array of indexes:

indxs = [1, 2, 4]

I know about values_at method, but it doesn't accept arrays, however, it can accept multiple values, proof: https://ruby-doc.org/core-2.5.1/Array.html#method-i-values_at

Maybe you could give me a clue how to deal with values_at. Thanks in advance!

EDIT: We've got 2 answers, so I I did a benchmark (1000 iterations, array.size = 20, indexes.size = 4)

                  user     system      total        real
values_at       0.004502   0.000000   0.004502 (  0.004476)
map[i]          0.005878   0.000000   0.005878 (  0.006968)

Md. Farhan Memon · Accepted Answer · 2019-04-19 09:05:56Z

9

You can splat the array as below:

my_arr = [121, 23, 46, 91, 38, 140]
indxs = [1, 2, 4]
my_arr.values_at(*indxs)
# => [23, 46, 38]

answered Apr 19, 2019 at 9:05

Md. Farhan Memon

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iGian · Accepted Answer · 2019-04-19 09:24:06Z

3

As alternative:

my_arr = [121, 23, 46, 91, 38, 140]
indxs = [1, 2, 4]

indxs.map { |i| my_arr[i] }
#=> [23, 46, 38]

answered Apr 19, 2019 at 9:24

iGian

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