Ruby: how to convert an array of strings into a hash?

Question

I need to convert an array like this:

codes = ["AAAA 2.0", "BBBB 1.0", "CCCC n/a", "DDDD"]

into a hash like this:

codes = {
  "AAAA" => "2.0",
  "BBBB" => "1.0",
  "CCCC" => "n/a",
  "DDDD" => ""
}

Any thoughts how to handle this the best way?

shivam · Accepted Answer · 2016-02-23 11:41:09Z

8

hash = {}
codes.each { |a| hash[a.split[0]] = a.split[1].to_s }
hash
#=> {"AAAA"=>"2.0", "BBBB"=>"1.0", "CCCC"=>"n/a", "DDDD"=>""}

Alternatively (if you are ok with "" being nil):

Hash[codes.map(&:split)]
#=> {"AAAA"=>"2.0", "BBBB"=>"1.0", "CCCC"=>"n/a", "DDDD"=>nil}

edited Feb 23, 2016 at 11:41

answered Feb 23, 2016 at 11:36

shivam

16.6k3 gold badges61 silver badges72 bronze badges

Sign up to request clarification or add additional context in comments.

6 Comments

Ilya Over a year ago

.map(&:split) looks better:)

shivam Over a year ago

yeah. I posted it as alternative solution because here "DDDD"=>nil.

Anthony Over a year ago

Interesting that [["DDDD"]].to_h raises an error but Hash[["DDDD"]] works successfully

msayen Over a year ago

@shivam - thank you. I've used: codes_h = Hash[codes.map(&:split)] but got an error: "invalid number of elements (3 for 1..2) (Argument error)".

shivam Over a year ago

@msayen that will happen only when an element in codes has 3 words, which was not part of your question example.

|

Cary Swoveland · Accepted Answer · 2016-02-25 09:42:41Z

codes.map { |s| s.split(/\s+/).tap { |a| a << "" if a.size==1 } }.to_h
  #=> {"AAAA"=>"2.0", "BBBB"=>"1.0", "CCCC"=>"n/a", "DDDD"=>""}

The steps are as follows.

codes.map { |s| s.split(/\s+/) }
  #=> [["AAAA", "2.0"], ["BBBB", "1.0"], ["CCCC", "n/a"], ["DDDD"]]

As we want to convert this to a hash, I would like to append an empty string to each of these arrays that are of size 1. Object#tap provides a convenient way of doing that:

b = codes.map { |s| s.split(/\s+/).tap { |a| a << "" if a.size==1 } }
  #=> [["AAAA", "2.0"], ["BBBB", "1.0"], ["CCCC", "n/a"], ["DDDD", ""]]

tap takes the result of s.split(/\s+/), represented by the block variable a and appends "" if it is of size 1. a is returned by tap, whether it has been altered or not. Lastly,

 b.to_h
   #=> {"AAAA"=>"2.0", "BBBB"=>"1.0", "CCCC"=>"n/a", "DDDD"=>""}

Collectives™ on Stack Overflow

Ruby: how to convert an array of strings into a hash?

2 Answers 2

6 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

6 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related