Sorting multidimensional array in Ruby

Question

I have an array :

[26] pry(#<HomeController>)> repos.class
=> Array
[27] pry(#<HomeController>)> repos.size
=> 2319
[28] pry(#<HomeController>)>

of Watchlists, which are composed of different types of elements :

[29] pry(#<HomeController>)> repos[0]
=> #<Watchlist _id: 4f82c1127c0c220001000002, _type: nil, searchable_values: ["description:grit", "description:gives", "description:you", "description:object", "description:oriented", "description:read", "description:write", "description:access", "description:to", "description:git", "description:repositories", "description:via", "description:ruby", "tag:git", "html_url:https", "html_url:github", "html_url:com", "html_url:mojombo", "html_url:grit"], arrangeable_values: {"description"=>"Grit gives you object oriented read/write access to Git repositories via Ruby.", "tag"=>"git", "html_url"=>"https://github.com/mojombo/grit"}, html_url: "https://github.com/mojombo/grit", description: "Grit gives you object oriented read/write access to Git repositories via Ruby.", forks: 269, watchers: 1536, created_at: 2007-10-29 14:37:16 UTC, pushed_at: 2012-09-04 21:54:09 UTC, avatar_url: "https://secure.gravatar.com/avatar/25c7c18223fb42a4c6ae1c8db6f50f9b?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-user-420.png", tags_array: ["git"], fork_: "false">

[30] pry(#<HomeController>)> repos[1]
=> #<Watchlist _id: 4f82c1127c0c220001000003, _type: nil, searchable_values: ["description:ruby", "description:process", "description:monitor", "html_url:https", "html_url:github", "html_url:com", "html_url:mojombo", "html_url:god"], arrangeable_values: {"description"=>"Ruby process monitor", "tag"=>"", "html_url"=>"https://github.com/mojombo/god"}, html_url: "https://github.com/mojombo/god", description: "Ruby process monitor", forks: 218, watchers: 1181, created_at: 2008-01-13 05:16:23 UTC, pushed_at: 2012-10-02 23:15:44 UTC, avatar_url: "https://secure.gravatar.com/avatar/25c7c18223fb42a4c6ae1c8db6f50f9b?d=https://a248.e.akamai.net/assets.github.com%2Fimages%2Fgravatars%2Fgravatar-user-420.png", tags_array: [], fork_: "false">

how can I sort Watchlists elements using Watchlist field named watchers ?

[31] pry(#<HomeController>)> repos[0].watchers
=> 1536
[29] pry(#<HomeController>)> repos[1].watchers
=> 1181
[32] pry(#<HomeController>)>

Mark Reed · Accepted Answer · 2012-11-30 11:38:28Z

2

repos.sort_by(&:watchers)

That returns the sorted array. To sort it in place, use sort_by! instead.

If it's possible that an element might not have a watchers method, you can try this instead:

repos.sort_by { |e| e.watchers rescue 0 }

If they're not all integers, you can convert them:

repos.sort_by { |e| e.watchers.to_i }

edited Nov 30, 2012 at 11:38

answered Nov 30, 2012 at 0:45

Mark Reed

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3 Comments

Luca G. Soave Over a year ago

that's what I did too, but I get back this : [31] pry(#<HomeController>)> repos.sort { |a, b| a.watchers <=> b.watchers } ArgumentError: comparison of Watchlist with Watchlist failed from /var/www/gitwatcher/vendor/bundle/ruby/1.9.1/bundler/gems/mongoid-be43b096e0a7/lib/mongoid/relations/proxy.rb:117:in `sort' [32] pry(#<HomeController>)>

Mark Reed Over a year ago

Do all of the elements have watchers? And is it really an integer, or does it just look like one?

Luca G. Soave Over a year ago

all elements have watchers, yes but they are not "clean" data type, sometimes they are integer, while sometimes they are strings ...

marcus erronius · Accepted Answer · 2012-11-30 00:47:18Z

1

It looks like you want Array#sortby:

repos.sort_by{|elem| elem.watchers }

It'll sort the array by the value of the "watchers" field.

answered Nov 30, 2012 at 0:47

marcus erronius

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1 Comment

Luca G. Soave Over a year ago

I get "ArgumentError: comparison of String with 461 failed" because some "elem.watchers" are of type "int" while others are "string". How can I convert it all in integers ?

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