Creating an array from an array of hashes in ruby

Question

I have an array of hashes.

rabbits = [{:color=>"blue", :height=>5, :name=>"Charles"}, {:color=>"red", :height=>12, :name=>"Henry"}, {:color=>"green", :height=>7, :name=>"Francis"}, {:color=>"purple", :height=>3, :name=>"William"}]

How would one create an array from this array of just the :height?

I tried: rabbits.map(&:height) and rabbits.map{|i| i.height} but neither worked.

Goal is to have height_array = [5, 12, 7, 3]

Sergio Tulentsev · Accepted Answer · 2012-10-13 09:46:40Z

6

This will work

rabbits.map{|c| c[:height] }

The other two methods that you tried expect height to be a method on c which is not the case.

edited Oct 13, 2012 at 9:46

answered Oct 12, 2012 at 7:32

Sergio Tulentsev

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4 Comments

rguerrettaz Over a year ago

Thank you so much! I tried that but was not storing it as a new array. So when I tried to print cats on the next line it was giving me the original. Thanks again.

Sergio Tulentsev Over a year ago

To rewrite the original array use cat.map! ... (note the exclamations mark). But I'd save it to another variable, ages = cats.map ...

rguerrettaz Over a year ago

Thanks Sergio. I did not know about that. Answer accepted. :)

rguerrettaz Over a year ago

I was asked to edit the question because it was part of a coding challenge and the curator was worried future students would be able to find this and use it for their answer. cats.map should equal rabbits.map and cats_age should equal height . Sorry for this inconvenience. :(

Salil · Accepted Answer · 2012-10-12 07:54:06Z

0

arr = cats.collect{|c| c[:cats_age] }

answered Oct 12, 2012 at 7:54

Salil

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2 Comments

Sergio Tulentsev Over a year ago

That's an alias for map, isn't it? :)

rguerrettaz Over a year ago

@Salil I was asked to edit the question because it was part of a coding challenge and the curator was worried future students would be able to find this and use it for their answer. cats.collect should equal rabbits.collect and cats_age should equal height . Sorry for this inconvenience. :(

saihgala · Accepted Answer · 2012-10-15 05:00:42Z

0

rabbits.inject([]) {|height,hash| height << hash[:height]}

edited Oct 15, 2012 at 5:00

answered Oct 12, 2012 at 7:32

saihgala

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3 Comments

Sergio Tulentsev Over a year ago

Seems to me that using inject is an overkill here :)

saihgala Over a year ago

indeed it is but just listed down as an option

rguerrettaz Over a year ago

@AshishSaihgal I was asked to edit the question because it was part of a coding challenge and the curator was worried future students would be able to find this and use it for their answer. cats.inject should equal rabbits.inject and cats_age should equal height . Sorry for this inconvenience. :(

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