Ruby: How to iterate over a range, but in set increments?

Question

So I'm iterating over a range like so:

(1..100).each do |n|
    # n = 1
    # n = 2
    # n = 3
    # n = 4
    # n = 5
end

But what I'd like to do is iterate by 10's.

So in stead of increasing n by 1, the next n would actually be 10, then 20, 30, etc etc.

Possible duplicate http://stackoverflow.com/questions/2583665/about-ruby-range — Diego Dias, Dec 03 '10 at 14:17

score 285 · Accepted Answer · answered Dec 03 '10 at 14:15

285

See http://ruby-doc.org/core/classes/Range.html#M000695 for the full API.

Basically you use the step() method. For example:

(10..100).step(10) do |n|
    # n = 10
    # n = 20
    # n = 30
    # ...
end

answered Dec 03 '10 at 14:15

Berin Loritsch

11,400
4
30
57

14

This answer led me to what I was looking for... If you have two times, you can do `(time1..time2).step(15.minutes) do |time|` – daybreaker Jan 18 '14 at 20:11

score 18 · Answer 2 · answered Feb 24 '14 at 22:09

18

You can use Numeric#step.

0.step(30,5) do |num|
  puts "number is #{num}"
end
# >> number is 0
# >> number is 5
# >> number is 10
# >> number is 15
# >> number is 20
# >> number is 25
# >> number is 30

answered Feb 24 '14 at 22:09

Arup Rakshit

116,827
30
260
317

score 9 · Answer 3 · answered Mar 11 '14 at 20:10

9

Here's another, perhaps more familiar-looking way to do it:

for i in (0..10).step(2) do
    puts i
end

answered Mar 11 '14 at 20:10

justsomeguy

131
1
1

14

Sorry, but the ruby style guide strongly discourages the use `for` loops. – Darth Egregious Apr 10 '15 at 16:58
@DarthEgregious why is that? – Doug Aug 12 '18 at 21:20
1

It's an extension of the philosophy that every _thing_ is an object and every _action_ is a method call. So rather than using a built-in for looping with `for`, you should use the `each` method. – Darth Egregious Aug 13 '18 at 15:13

score 7 · Answer 4 · edited Oct 05 '13 at 10:31

rng.step(n=1) {| obj | block } => rng

Iterates over rng, passing each nth element to the block. If the range contains numbers or strings, natural ordering is used. Otherwise step invokes succ to iterate through range elements. The following code uses class Xs, which is defined in the class-level documentation.

range = Xs.new(1)..Xs.new(10)
range.step(2) {|x| puts x}
range.step(3) {|x| puts x}

produces:

1 x
3 xxx
5 xxxxx
7 xxxxxxx
9 xxxxxxxxx
1 x
4 xxxx
7 xxxxxxx
10 xxxxxxxxxx

Reference: http://ruby-doc.org/core/classes/Range.html

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Ruby: How to iterate over a range, but in set increments?

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