Python's enumerate in Ruby?

Question

def enumerate(arr):
    (0..arr.length - 1).to_a.zip(arr)

Is something built in for this? It doesn't need to have it's members immutable, it just needs to be in the standard library. I don't want to be the guy who subclasses the Array class to add a Python feature to a project.

Does it have a different name in Ruby?

%w(a b c).enumerate
=> [[0, "a"], [1, "b"], [2, "c"], [3, "d"]]

score 37 · Accepted Answer · answered Dec 18 '12 at 16:10

37

Something like this in Python:

a = ['do', 're', 'mi', 'fa']
for i, s in enumerate(a):
    print('%s at index %d' % (s, i))

becomes this in Ruby:

a = %w(do re mi fa)
a.each_with_index do |s,i|
    puts "#{s} at index #{i}"
end

answered Dec 18 '12 at 16:10

snurre

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1

`a = 'do re mi fa'.split()` might be closer to the Ruby version – Antimony Apr 08 '13 at 14:57

score 8 · Answer 2 · answered Dec 18 '12 at 16:08

8

Assuming it's for enumeration, each_with_index can do that. Or if you have an Enumerator, just use with_index.

answered Dec 18 '12 at 16:08

Ry-

218,210
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score 7 · Answer 3 · answered Dec 18 '12 at 16:18

7

Maybe a quicker solution would be :

%w(a b c).map.with_index {|x, i| [i, x] }

answered Dec 18 '12 at 16:18

Raindal

3,227
15
14

Hey...that looks more familiar `;)`. – yurisich Dec 18 '12 at 16:28

score 2 · Answer 4 · answered Nov 20 '20 at 15:20

2

A fun one!

a = %w(do re mi fa)
a.length.times.zip a

answered Nov 20 '20 at 15:20

Stev-0

31
1

In python, this would be `zip(range(len(a)), a)` just in case you're like me and had to run `irb` to catch on to this clever use of `.times`. Very nice – yurisich Nov 20 '20 at 17:11

Python's enumerate in Ruby?

4 Answers4