Sort array of hash in ruby

Question

I have an array of hash like this:

[{683=>5}, {689=>2}, {692=>10}]

I want the result like this:

[{692=>10}, {683=>5}, {689=>2}]

Could any one help me?

falsetru · Accepted Answer · 2014-02-07 14:58:54Z

4

Use Enumerable#sort_by. The return value of the block is used as comparison key.

[{683=>5}, {689=>2}, {692=>10}].sort_by { |h| -h.values[0] }
# => [{692=>10}, {683=>5}, {689=>2}]

answered Feb 7, 2014 at 14:58

falsetru

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5 Comments

toro2k Over a year ago

Try sort_by { |h| h.values[0] }.reverse!, surprisingly it is slighlty faster and a little clearer, IMHO.

falsetru Over a year ago

@toro2k, I just tried it with fruity in Windows 7 64bit, ruby 2.0. It says both are similar.

toro2k Over a year ago

On my Debian box fruity reports a 10% difference, well, it seems to be just a little clearer... :-)

Abdo Over a year ago

It looks like reverse is faster by 10% for me as well (on osx). I had an array of 10,000 hashes and ran each test 100 times in fruity.

falsetru Over a year ago

@toro2k, I got it. Both decorate(in decorate-sort-undecorate), reverse! take O(n) times. But decorate is performed in ruby loop, while reverse! is performed in C. More operations in the block means caused visible time difference.

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