Formatting Numbers

Ruby
1

This has got to be simple but I checked the PickAxe and Google to no
avail.
My guess is that I’m looking for it in terms that don’t make sense.

Anyway…

I have a fixnum:

a = 1000

I would like to output it with a comma, such as “1,000”. Is there a
formatting class or something I can use something along these lines
(thinking from my Java background):

Formatter f = Formatter.new(“N0”)
puts f(a)

Any help appreciated.

Thanks,
Hunter

2

On Feb 8, 2006, at 8:43 PM, HH wrote:

I would like to output it with a comma, such as “1,000”. Is there a

I dunno know about some kind of builtin format object (I imagine
maybe the right incantation of sprintf could do it) but heres a
method (kinda long for what it is, theres probably some regex to do
it in one fell swoop):

% cat commify.rb
require ‘enumerator’
def commify(num)
str = num.to_s
a = []
str.split(//).reverse.each_slice(3) { |slice| a << slice }
new_a = []
a.each do |item|
new_a << item
new_a << [","]
end
new_a.delete_at(new_a.length - 1)
new_a.flatten.reverse.join
end

p commify(1000)
p commify(100)
p commify(1_000_000)
p commify(1024)

% ruby commify.rb
“1,000”
“100”
“1,000,000”
“1,024”

3

Or

irb(main):001:0> class Integer
irb(main):002:1> def commify
irb(main):003:2> self.to_s.gsub(/(\d)(?=(\d{3})+$)/,’\1,’)
irb(main):004:2> end
irb(main):005:1> end
=> nil
irb(main):006:0> 1000.commify
=> “1,000”
irb(main):007:0> 100.commify
=> “100”
irb(main):008:0> 1_000_000.commify
=> “1,000,000”
irb(main):009:0> 1024.commify
=> “1,024”

Kent

4

On Feb 8, 2006, at 9:27 PM, David V. wrote:

Now if only we directly had a method to slice an Array into an
Array of
slices, the whole thing could turn into a one-liner. Which I hate,
but in a
good way.

David V.

str.split(//).reverse.to_enum(:each_slice,3).to_a

5

hello,

there is even bigger problem: the formatting that you are looking for
depends on locale, and as far as i could tell ruby does not provide any
support for that. so the solutions that people suggested would work only
for
american formatting, and as soon as you choose to change your formatting
and
use comma for decimal point you are at the square one…

konstantin

“HH” [email protected] wrote in message
news:[email protected]…

6

On Feb 8, 2006, at 7:43 PM, HH wrote:

I would like to output it with a comma, such as “1,000”. Is there a
formatting class or something I can use something along these lines
(thinking from my Java background):

Formatter f = Formatter.new(“N0”)
puts f(a)

Any help appreciated.

def commify( str )
str.reverse.gsub(/(\d\d\d)(?=\d)(?!\d*.)/,’\1,’).reverse
end

Handles floats too.

James Edward G. II

7

DÅ?a Å tvrtok 09 Február 2006 03:11 Logan C. napísal:

Hunter
a = []
p commify(1000)
p commify(100)
p commify(1_000_000)
p commify(1024)

% ruby commify.rb
“1,000”
“100”
“1,000,000”
“1,024”

Hmm, I was in the middle of writing precisely this sort of hack as this
arrived. That said, much better job here. The #each_slice comes from the
enumerator library? I should really learn to use that one…

That said, I’m almost sure you can golf that thing down a bit. How
about:

require 'enumerator'
def commify(num)
	str =  num.to_s
	a = []
	str.split(//).reverse.each_slice(3) { |slice| a << slice }
	a.reverse.collect{|i| i.reverse.join}.join(",")
end

p commify(1000)
p commify(100)
p commify(1_000_000)
p commify(1024)

Now if only we directly had a method to slice an Array into an Array of
slices, the whole thing could turn into a one-liner. Which I hate, but
in a
good way.

David V.

8

Thanks to everyone for all the great suggestions.

I really appreciate it.

9

HH wrote:

I have a fixnum:

a = 1000

I would like to output it with a comma, such as “1,000”. Is there a
formatting class or something I can use something along these lines
(thinking from my Java background):

http://extensions.rubyforge.org/rdoc/classes/Numeric.html#M000011

10

Hmm.

Anyone have any experience with that?

David V.

DÅ?a Å tvrtok 09 Február 2006 04:28 konsu napísal:

11

Logan C. wrote:

On Feb 8, 2006, at 9:27 PM, David V. wrote:

Now if only we directly had a method to slice an Array into an
Array of
slices, the whole thing could turn into a one-liner. Which I hate,
but in a
good way.

David V.

str.split(//).reverse.to_enum(:each_slice,3).to_a

The one above from Logan didn’t work for me.

But this one from James Edward G. II did:
str.reverse.gsub(/(\d\d\d)(?=\d)(?!\d*.)/,’\1,’).reverse

Thanks to both.