Ruby equivalent of Python's conventional number separation

Question

In Python, we have something like print(f'{int(input()):,}') that separates numbers by commas. That is for example, if we provide the input of 70671891032 we get 70,671,891,032. Is there anything similar to this in Ruby (without the use of regex)?

In Rails / active support, there is a method `number_with_delimiter` (see https://stackoverflow.com/a/1078366/2981429) but I'm not sure there's one in plain Ruby. — max pleaner, Feb 05 '21 at 07:52
If you're not using Rails you can load the method from the `activesupport` gem: https://api.rubyonrails.org/classes/ActiveSupport/NumberHelper.html#method-i-number_to_delimited ... this gem contains a ton of useful core extensions — max pleaner, Feb 05 '21 at 07:54
ActiveSupport uses regex, so, I could infere that Ruby doesn't have what you are looking for. https://github.com/rails/rails/blob/main/activesupport/lib/active_support/number_helper/number_to_delimited_converter.rb — iGian, Feb 05 '21 at 07:57

score 1 · Answer 1 · answered Feb 05 '21 at 08:19

1

Ruby's built-in string formatting doesn't have an option for a thousands separator.

If you don't want to use regular expressions, you could insert a separator every 3 characters from the right, e.g. via step:

input = 70671891032

string = input.to_s

(string.size - 3).step(1, -3) do |i|
  string.insert(i, ',')
end

string
#=> "70,671,891,032"

answered Feb 05 '21 at 08:19

Stefan

109,145
14
143
218

Does this really make sense? After all, the separator depends on the locale and is not necessarily a `,`. This point is also a bit unclear from the OPs question: Does he **always** wants to use a comma, or did he give this just as an example. – user1934428 Feb 05 '21 at 09:49

score 0 · Answer 2 · answered Feb 05 '21 at 09:45

I expect this is not what you were looking for, but it does convert a non-negative integer to a string of digits with thousands separators.

def commafy(n)
  s = ''
  loop do
    break s if n.zero? 
    n, n3 = n.divmod(1000)   
    s[0,0] = (n.zero? ? ("%d" % n3) : (",%03d" % n3)) 
  end
end

input = 70671891032

commafy(input)
  #=> "70,671,891,032"

Ruby equivalent of Python's conventional number separation

2 Answers2