How can I get the number of instances of a value in a Rails array?

Question

Say I have an array like this:

["white", "red", "blue", "red", "white", "green", "red", "blue", "white", "orange"]

I want to go through the array and create a new array containing each individual color and the amount of times it appeared in the original array.

So, in the new array it would report that "white" appeared 3 times, "blue" appeared 2 times and so on...

How should I go about doing this?

Answer 1

counts = Hash.new(0)
colors.each do |color|
    counts[color] += 1
end

Answer 2

better return a hash...

def arr_times(arr)
  arr.inject(Hash.new(0)) { |h,n| h[n] += 1; h }
end

Answer 3

result = {}
hash = array.group_by{|item| item}.each{|key, values| result[key] = values.size}
p result

Answer 4

I see you tagged the question with ruby-on-rails.

If this is a database model/column (e.g., User model with color attribute) you should be doing the computation in the DB:

 User.count(:all,:group=>:color).sort_by {|arr| -arr[1]}