Reformatting a string of numbers in Ruby

Question

In our application we have a string of digits (stored as a String) for a registration number (Australian Business Number or Australian Company Number, similar to a SSN), for example:

"98123123999"

When we display this information in our web application it would be nice to be able to reformat the digits to be more readable, e.g.:

98 123 123 999

In ruby the best solution I have so far is to:

Check the length
Format the string by using the slice operator: [a[0,2], a[2,3], a[5,3], a[8, 3]].join(" ")

However this smells and doesn't seem right.

Whats the best way to do something seemingly so simple?

Edit: I should note as well that the string of numbers could be prefixed with a 0 (e.g. "012345678901") so it isn't possible to parse it as an integer then use format strings.

Prasad Surase · Accepted Answer · 2012-10-11 07:03:03Z

4

use

a = "98123123999"
=> "98123123999" 
b = a.split('').insert(2, ' ').insert(6, ' ').insert(10, ' ')
=> "9", "8", " ", "1", "2", "3", " ", "1", "2", "3", " ", "9", "9", "9"] 
b = a.split('').insert(2, ' ').insert(6, ' ').insert(10, ' ').join
=> "98 123 123 999"

or if u want the string to be modified

a = "98123123999"
=> "98123123999" 
b = a.insert(2, ' ').insert(6, ' ').insert(10, ' ')
=> "98 123 123 999" 
a
=> "98 123 123 999"

answered Oct 11, 2012 at 7:03

Prasad Surase

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1 Comment

Matthew Savage Over a year ago

Thats perfect, and seems pretty efficient. Given the strings are transient modification is not an issue. Thanks!

Benoît · Accepted Answer · 2012-10-11 07:34:12Z

4

For a more generic point of view, if you use rails, you can use number_with_delimiter(number, delimiter=",", separator=".").

Otherwise, maybe just write something based on its source code.

number.to_s.gsub!(/(\d)(?=(\d{3})+(?!\d))/, "\\1#{' '}")

>> 1234567890.to_s.gsub!(/(\d)(?=(\d{3})+(?!\d))/, "\\1#{' '}")
=> "1 234 567 890"

edited Oct 11, 2012 at 7:34

answered Oct 11, 2012 at 7:11

Benoît

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4 Comments

Prasad Surase Over a year ago

suppose i have a number 1234512345. i want it to be displayed as '12345 12345'. how can i use the number_with_delimiter method here. an example would be really good.

Benoît Over a year ago

@surase.prasad Edited my answer. You just replace the 3 with the 5 and you are good to go.

Mladen Jablanović Over a year ago

Umm, any reason why you interpolate a space into a string instead just writing "\\1 "?

Benoît Over a year ago

@MladenJablanović Just follower the rails source code. Did not try to improve or change it.

halfelf · Accepted Answer · 2012-10-11 07:01:35Z

1

Try this:

def format_digit(s, acc="")
  if s.size > 3
    new_acc = s[-3..-1] + " " +acc
    format_digit(s[0...-3], new_acc)
  else
    s + " " + acc
  end
end

s = "98123123999"
puts format_digit(s)

answered Oct 11, 2012 at 7:01

halfelf

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Comments

Filipe Miguel Fonseca · Accepted Answer · 2012-10-11 08:06:21Z

1

Not sure this suits your needs cause the group of two digits comes in the end instead of the beginning...

"98123123999".scan(/.{1,3}/).join(' ') #=> "981 231 239 99"

answered Oct 11, 2012 at 8:06

Filipe Miguel Fonseca

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Comments

saihgala · Accepted Answer · 2012-10-11 07:13:40Z

0

str           = "098123123999"
formatted_arr = []

if str.length % 3 == 0
    (str.length/3).times { formatted_arr << str.slice!(0..2) }
else
    formatted_arr << str.slice!(0..str.length % 3 - 1)
    (str.length/3).times { formatted_arr << str.slice!(0..2) }
end

puts formatted_arr.join(" ") # 098 123 123 999

answered Oct 11, 2012 at 7:13

saihgala

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