Sort an array of objects by number of occurrences and remove duplicates

Question

Model.find_by_tag_name("#foo") returns an array with:

25 records with tag_name = "#foo"
40 records with tag_name = "#foobar"
15 records with tag_name = "#foobarbaz"

I want to count the number of times each unique tag_name showed up, sort the results by that count, then eliminate duplicates. The resulting order should be:

#foobar
#foo
#foobarbaz

Currently I'm doing something like this to get the uniques and a count:

counter = Hash.new(0)
uniques = results.each{|tag| counter[tag.tag_name] += 1 }.uniq{|tag| tag.tag_name }

The above makes counter => {"#foo"=>25, "#foobar"=>40, "#foobarbaz"=>15}.

Having retrieved, de-duped and counted the results, what approaches might I take to sorting the resulting array of unique tags(uniques) by the number of times they showed up?

DigitalRoss · Accepted Answer · 2012-12-01 00:03:39Z

2

{"#foo"=>25, "#foobar"=>40, "#foobarbaz"=>15}.sort_by { |k, v| -v }.map(&:first)

answered Dec 1, 2012 at 0:03

DigitalRoss

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2 Comments

Chris Cashwell Over a year ago

I should have been more clear- I don't want to sort counter, but rather the array of unique results.

akuhn Over a year ago

@ChrisCashwell did you even run the code? Ross’s first answer does return what you are looking for.

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