aggregate values from specific key in an array of hashes

Question

I'm trying to build an array of values that come from an array of hashes, at the moment my code looks like this:

ids = array_of_hashes.inject([]) do |result,instance|
    result << instance[:id]
    result
end

I just want to know if there's a more efficient way to do it?

no, just making it more obvious as to what it is, that isn't my code exactly just simplified to show what I currently have. — Thermatix, Apr 28 '15 at 13:57
`array_of_hashes` or simply `hashes` would be obvious, `hash` is somewhat misleading. — Stefan, Apr 28 '15 at 13:59

score 4 · Answer 1 · answered Apr 28 '15 at 13:14

4

You could change it to look like:

ids = hash.map { |instance| instance[:id] }

Not necessarily more efficient, but easier to read and maintain!

Good luck!

answered Apr 28 '15 at 13:14

Paweł Dawczak

score 1 · Accepted Answer · edited May 23 '17 at 11:59

1

There are two easy ways for it:

 1. ids = hash.collect{|h| h[:id]} 
 2. ids = hash.map{|h| h[:id]}

Now you would ask what is the difference in both? for explanation see this accepted answer

edited May 23 '17 at 11:59

Community

answered Apr 28 '15 at 13:44

Abdul Baig

I will tick this as correct simply because It possess both ways (even if the only difference is that one is an alias of the other) and has a source link for information, the other answer is still however correct. – Thermatix Apr 28 '15 at 13:56

2 Answers2