What is the best way to chop a string into chunks of a given length in Ruby?

Question

I have been looking for an elegant and efficient way to chunk a string into substrings of a given length in Ruby.

So far, the best I could come up with is this:

def chunk(string, size)
  (0..(string.length-1)/size).map{|i|string[i*size,size]}
end

>> chunk("abcdef",3)
=> ["abc", "def"]
>> chunk("abcde",3)
=> ["abc", "de"]
>> chunk("abc",3)
=> ["abc"]
>> chunk("ab",3)
=> ["ab"]
>> chunk("",3)
=> []

You might want chunk("", n) to return [""] instead of []. If so, just add this as the first line of the method:

return [""] if string.empty?

Would you recommend any better solution?

Answer 1

Are there some other constraints you have in mind? Otherwise I'd be awfully tempted to do something simple like

[0..10].each {
   str[(i*w),w]
}

Answer 2

test.split(/(...)/).reject {|v| v.empty?}

The reject is necessary because it otherwise includes the blank space between sets. My regex-fu isn't quite up to seeing how to fix that right off the top of my head.

Answer 3

Use String#scan:

>> 'abcdefghijklmnopqrstuvwxyz'.scan(/.{4}/)
=> ["abcd", "efgh", "ijkl", "mnop", "qrst", "uvwx"]
>> 'abcdefghijklmnopqrstuvwxyz'.scan(/.{1,4}/)
=> ["abcd", "efgh", "ijkl", "mnop", "qrst", "uvwx", "yz"]
>> 'abcdefghijklmnopqrstuvwxyz'.scan(/.{1,3}/)
=> ["abc", "def", "ghi", "jkl", "mno", "pqr", "stu", "vwx", "yz"]