Ruby Hash to array of values

Question

I have this:

hash  = { "a"=>["a", "b", "c"], "b"=>["b", "c"] } 

and I want to get to this: [["a","b","c"],["b","c"]]

This seems like it should work but it doesn't:

hash.each{|key,value| value}
=> {"a"=>["a", "b", "c"], "b"=>["b", "c"]} 

Any suggestions?

Solution 1

Also, a bit simpler....

>> hash = { "a"=>["a", "b", "c"], "b"=>["b", "c"] }
=> {"a"=>["a", "b", "c"], "b"=>["b", "c"]}
>> hash.values
=> [["a", "b", "c"], ["b", "c"]]

Ruby doc here

Solution 2

I would use:

hash.map { |key, value| value }

Solution 3

hash.collect { |k, v| v }
#returns [["a", "b", "c"], ["b", "c"]] 

Enumerable#collect takes a block, and returns an array of the results of running the block once on every element of the enumerable. So this code just ignores the keys and returns an array of all the values.

The Enumerable module is pretty awesome. Knowing it well can save you lots of time and lots of code.

Solution 4

It is as simple as

hash.values
#=> [["a", "b", "c"], ["b", "c"]]

this will return a new array populated with the values from hash

if you want to store that new array do

array_of_values = hash.values
#=> [["a", "b", "c"], ["b", "c"]]

array_of_values
 #=> [["a", "b", "c"], ["b", "c"]]

Solution 5

hash  = { :a => ["a", "b", "c"], :b => ["b", "c"] }
hash.values #=> [["a","b","c"],["b","c"]]

View more solutions

Comments

[tadman]

Don't forget that, like @Ray Toal's answer, hash.values is ultimately the correct answer here.

[Michael Durrant]

+! Nifty! I will upvote despite having a competing answer (using map), cos I like this a lot!

[Mark Thomas]

I didn't downvote it, but it's a more complicated equivalent to Hash#values.

[Michael Durrant]

Yes, I also upvoted Ray's answer. I'm happy to upvote a competing answer when I like it too.

[jordanbtucker]

Hash#values is not only simpler, but more efficient. Compare time ruby -e '(1..1000000).reduce({}){|h,i| h.store i,i; h}.values' with time ruby -e '(1..1000000).reduce({}){|h,i| h.store i,i; h}.map{|k,v| v}'

[Romans 8.38-39]

+1 (Dazzled amazingly after I tried your code) I spent one day with no luck removing the index using many methods... All I can say thank you very much!!! :D

[Jaap Haagmans]

Or hash.map(&:second) :)

[stack1]

Are the keys printed in the exact order which they occur ?

[karlingen]

stackoverflow.com/posts/12771873/revisions as you can see the formatting of your code was way off

[witkacy26]

I think we are not competing here but helping each other, right? :)

[Fabian]

Exactly what I was looking for when trying to create an array from a hash using it's keys as values. Thanks :)

[Chris Cirefice]

Useful when you need to also do some logic with the keys at the same time.

[Sylvain]

A more in depth explanation brianstorti.com/understanding-ruby-idiom-map-with-symbol

[Ethan Chen]

Since you're not using the key variable, you can even do hash.map { |_, value| value }

[tobixen]

Upvoted. Although hash.values is a more appropriate answer to the actual question asked, this answer helped me in the problem I was googling for.