CODEWITHSUNDEEP
rubyarraysloops
m.silenus
m.silenus

Reputation: 492

Best way to iterate over multiple arrays?

What's is the best (beauty and efficient in terms of performance) way to iterate over multiple arrays in Ruby? Let's say we have an arrays:

a=[x,y,z]
b=['a','b','c']

and I want this:

x a
y b
z c

Thanks.

Upvotes: 7

Views: 3625

Answers (5)

Rob O B
Rob O B

Reputation: 11

I like to use transpose when iterating through multiple arrays using Ruby. Hope this helps.

bigarray = []
bigarray << array_1
bigarray << array_2
bigarray << array_3
variableName = bigarray.transpose

variableName.each do |item1,item2,item3|

# do stuff per item
# eg 
puts "item1"
puts "item2"
puts "item3"

end

Upvotes: 1

Dylan Markow
Dylan Markow

Reputation: 124419

An alternative is using each_with_index. A quick benchmark shows that this is slightly faster than using zip.

a.each_with_index do |item, index|
  puts item, b[index]
end

Benchmark:

a = ["x","y","z"]
b = ["a","b","c"]

Benchmark.bm do |bm|
  bm.report("ewi") do
    10_000_000.times do
      a.each_with_index do |item, index|
        item_a = item
        item_b = b[index]
      end
    end
  end
  bm.report("zip") do
    10_000_000.times do
      a.zip(b) do |items|
        item_a = items[0]
        item_b = items[1]
      end
    end
  end
end

Results:

      user     system      total        real
ewi  7.890000   0.000000   7.890000 (  7.887574)
zip 10.920000   0.010000  10.930000 ( 10.918568)

Upvotes: 6

kurumi
kurumi

Reputation: 25599

>> a=["x","y","z"]
=> ["x", "y", "z"]
>> b=["a","b","c"]
=> ["a", "b", "c"]
>> a.zip(b)
=> [["x", "a"], ["y", "b"], ["z", "c"]]
>>

Upvotes: 2

kelloti
kelloti

Reputation: 8951

The zip method on array objects:

a.zip b do |items|
    puts items[0], items[1]
end

Upvotes: 4

Gaslight Deceive Subvert
Gaslight Deceive Subvert

Reputation: 20372

See What is a Ruby equivalent for Python's "zip" builtin?

Upvotes: 1

Related Questions