get each individual number from a Fixnum integer Ruby on Rails

Question

This is a real ultra newbie question.

I have an age stored in a database.

When I get the age from the database I want to get each individual digit.

Example:

User.age = 25

I want to get the following:

first = 5
second = 2

I can't seem to wrestle this from the data as its a fix num.

Anyone know a clean and simple solution.

score 19 · Accepted Answer · edited May 23 '17 at 12:17

19

You can convert to a string and then split into digits e.g.

first, second = User.age.to_s.split('')
=> ["2", "5"]

If you need the individual digits back as Fixnums you can map them back e.g.

first, second = User.age.to_s.split('').map { |digit| digit.to_i }
=> [2, 5]

Alternatively, you can use integer division e.g.

first, second = User.age.div(10), User.age % 10
=> [2, 5]

Note that the above examples are using parallel assignment that you might not have come across yet if you're new to Ruby.

edited May 23 '17 at 12:17

Community

1
1

answered Mar 21 '11 at 13:16

mikej

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5

`map { |digit| digit.to_i }` shortcut => `map(&:to_i)` – fl00r Mar 21 '11 at 13:42
3

Also: `n.to_s.chars.map(&:to_i)`. – tokland May 05 '13 at 12:56
In your case, you can also use the divmod method. I prefer the Integer#digits method btw, `1234.digits # => [4, 3, 2, 1]` – 15 Volts Oct 07 '19 at 07:36

score 11 · Answer 2 · answered Dec 25 '16 at 11:39

11

Ruby 2.4 has Integer#digits method. eg:

25.digits
# => [5, 2]

So you can do

first, second = user.age.digits

answered Dec 25 '16 at 11:39

Santhosh

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Perfect, best solution for now – Lucas Andrade Jan 12 '19 at 23:50
2

Note it returns the digits in 'reverse' order, meaning from the number 25, the 0th digit returned in the array is 5, not 2 – andrewcockerham Apr 20 '19 at 20:30

score 7 · Answer 3 · answered Mar 21 '11 at 13:30

7

first, last = User.age.divmod(10)

answered Mar 21 '11 at 13:30

steenslag

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this doesn't return the first digit if the users age has three digits – Zippie Apr 24 '13 at 23:16

score 4 · Answer 4 · answered Aug 15 '13 at 08:44

4

Check out benchmarks for a lot of solutions here: http://gistflow.com/posts/873-integer-to-array-of-digits-with-ruby The best one is to use divmod in a loop:

def digits(base)
  digits = []

  while base != 0 do
    base, last_digit = base.divmod(10)
    digits << last_digit
  end

  digits.reverse
end

answered Aug 15 '13 at 08:44

makaroni4

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Nice, but as a general purpose method, this has a flaw: It will return `[]` for `0`. This can be fixed by replacing `while base != 0` with `loop`, and adding `return digits.reverse if base == 0` to the bottom of that loop, instead of the return value outside the loop. It will still however loop infinitely for negative numbers. – daniero Jul 20 '15 at 16:27

score 3 · Answer 5 · answered Mar 21 '11 at 13:16

3

http://www.ruby-doc.org/core/classes/String.html#M001210

 25.to_s.each_char {|c| print c, ' ' }

This stuff is really easy to find through Ruby docs.

answered Mar 21 '11 at 13:16

thenengah

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I was converting to a string and then used the string[0].chr. I thought that there must be a better way. That divmod(10) is pretty cool and compact. – chell Mar 21 '11 at 14:00

score 1 · Answer 6 · answered Mar 21 '11 at 13:49

1

Not the best solution, but just for collection:

User.age.chars.to_a.map(&:to_i)
#=> [5, 2]
first, second = User.age.chars.to_a.map(&:to_i)

answered Mar 21 '11 at 13:49

fl00r

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get each individual number from a Fixnum integer Ruby on Rails

6 Answers6