CODEWITHSUNDEEP
arraysrubystringinteger
Misha Krul
Misha Krul

Reputation: 397

Making a Ruby array string into an array of integers

I have an array (which is technically a string) of id numbers.

ids = "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]"

I want to make the ids into an array that looks like this:

ids = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

The only way I've found to do this is to use map.

id_numbers = ids.split(/,\s?/).map(&:to_i)

However, this lops off the first number in the array and replaces it with 0.

id_numbers = [0, 2, 3, 4, 5, 6, 7, 8, 9, 10]

Is there a better way to go about converting a string array into a regular array?

Upvotes: 1

Views: 885

Answers (3)

MOPO3OB
MOPO3OB

Reputation: 401

To summarize: you get 0 as first element in the array because of non-digital character at the beginning of your string:

p '[1'.to_i         #=> 0

Maybe there is a better way to recieve original string. If there is no other way to recieve that string you can simply get rid off first character and your own solution will work:

ids = "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -11]"

p ids[1..-1].split(",").map(&:to_i)
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -11]

@tadman's and @CarySwoveland's solutions work perfectly fine. Alternatively:

ids = "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -11]"

p ids.tr("^-0-9", ' ').split.map(&:to_i)
# [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, -11]

Keep in mind that &: first appeared in Ruby 1.8.7.

Upvotes: 0

Cary Swoveland
Cary Swoveland

Reputation: 110755

If you do not wish to use JSON,

ids.scan(/\d+/).map(&:to_i)
  #=> [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]

If ids may contain the string representation of negative integers, change the regex to /-?\d+/.

Upvotes: 3

tadman
tadman

Reputation: 211750

Since this is actually in JSON format the answer is easy:

require 'json'

id_json = "[1, 2, 3, 4, 5, 6, 7, 8, 9, 10]"

ids = JSON.load(id_json)

The reason your solution "lops off" the first number is because of the way you're splitting. The first "number" in your series is actually "[1" which to Ruby is not a number, so it converts to 0 by default.

Upvotes: 5

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