Create an Array of Fixed Length Given an Array of Arbitrary Length

Question

I'm looking to write a method that creates an array of a fixed length (in my case 12) from any array it is provided of arbitrary length (though the length will always be 12 or less) by repeating the objects in order.

So for example given the array a:

a = [1, 2, 3, 4]

I would want to have returned:

a = [1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4]

Another example:

b = ["peach", "plumb", "pear", "apple", "banana", "orange"]

Would return:

b = ["peach", "plumb", "pear", "apple", "banana", "orange", "peach", "plumb", "pear", "apple", "banana", "orange"]

And so on. If given an array with 12 objects, it would just return the same array.

The methods I've written to accomplish this so far have been very ugly and not very Rubyish; interested in how others would handle this.

Thanks in advance.

BaroqueBobcat · Accepted Answer · 2010-02-02 23:33:26Z

15

In 1.8.7 & 1.9 you can do cool stuff with Enumerators

a = [1,2,3,4]
#=> [1,2,3,4]
a.cycle.take 12
#=> [1, 2, 3, 4, 1, 2, 3, 4, 1, 2, 3, 4]

answered Feb 2, 2010 at 23:33

BaroqueBobcat

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3 Comments

tfwright Over a year ago

did not know that--very nice.

Marc-André Lafortune Over a year ago

Very nice. FOr Ruby 1.8.6, just require 'backports'

btw Over a year ago

Wow, would have never known about this. Perfect.

tfwright · Accepted Answer · 2010-02-02 23:16:56Z

4

Array.new(12).fill(some_array).flatten[0..11]

answered Feb 2, 2010 at 23:16

tfwright

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Comments

Trevoke · Accepted Answer · 2010-02-02 20:22:23Z

3

def twelvify array
  array += array while array.size < 12
  array[0..11]
end

It's also a bit ugly but it's, at least, simple. :-)

answered Feb 2, 2010 at 20:22

Trevoke

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3 Comments

btw Over a year ago

Awesome, thanks! This is definitely a cleaner version of what I was coming up with.

James A. Rosen Over a year ago

I love that the method is called :twelvify :)

Trevoke Over a year ago

chuckle Yep, I definitely got a good Rubyish name for it, but I have to admit that I like BarqueBobcat's answer a lot more than mine! :)

sepp2k · Accepted Answer · 2010-02-02 21:26:19Z

1

array * (12/array.size) + array[0, (12 % array.size)]

edited Feb 2, 2010 at 21:26

answered Feb 2, 2010 at 20:26

sepp2k

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3 Comments

Trevoke Over a year ago

Exactly what the OP asked for, but dear $deity it's ugly :)

Farrel Over a year ago

How about: array * (12/array.size + 1))[0,12]

Wayne Conrad Over a year ago

@sepp2k, did you mean ... instead of ..?

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