I have a Hash which is of the form
{:a => {"aa" => 11,"ab" => 12}, :b => {"ba" => 21,"bb" => 22}}
How do i convert it to the form {:a => [["aa",11],["ab",12]],:b=>[["ba",21],["bb",22]]}
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If you're working with multi-level hashes and you want to flatten them check out my HashModel gem: rubygems.org/gems/hashmodel and you can get the source on github: github.com/mikbe/hashmodelMike Bethany– Mike Bethany2011-01-04 20:42:46 +00:00Commented Jan 4, 2011 at 20:42
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3 Answers
If you want to modify the original hash you can do:
hash.each_pair { |key, value| hash[key] = value.to_a }
From the documentation for Hash#to_a
Converts hsh to a nested array of [ key, value ] arrays.
h = { "c" => 300, "a" => 100, "d" => 400, "c" => 300 }
h.to_a #=> [["c", 300], ["a", 100], ["d", 400]]
3 Comments
Aditya Manohar
Thank you @mikej. Worked like a charm, though I'd like to know what the difference between hash.each and hash.each_pair is ?
Thiago Silveira
If you don't want to modify the original hash, you can use this:
new_hash = hash.inject({}) { |h, (key, value)| h[key] = value.to_a; h }
Christopher Creutzig
@Aditya: If you want your block to get two parameters, use
each_pair. If only for readability.Here is another way to do this :
hsh = {:a => {"aa" => 11,"ab" => 12}, :b => {"ba" => 21,"bb" => 22}}
hsh.each{|k,v| hsh[k]=*v}
# => {:a=>[["aa", 11], ["ab", 12]], :b=>[["ba", 21], ["bb", 22]]}
Comments
hash.collect {|a, b| [a, hash[a].collect {|c,d| [c,d]}] }.collect {|e,f| [e => f]}
