RoR array -count identical elements-on including value

Question

how do we count idential values on after appending value in to array

such that

a=[]

a<<1 count of 1 is 1

a<<1 count of 1 is 2

thanks

Answer 1

You could do:

a.select{|v| v == 1}.size

It's only one solution

Answer 2

Someone will probably come up with a more specialized solution, but I would just reduce it

counts = [1,3,3].reduce({}) do |acc,n|
  acc.tap do |a|
    a[n] ||= 0
    a[n] += 1
  end
end

counts.each {|k,v| puts "#{k} was found #{v} times"}

(note that tap is ruby 1.9, and is backported in activesupport)

output of that will be

1 was found 1 times
3 was found 2 times

Answer 3

a = [1,2,3,4,5,1,2,2,3,4]

=> [1, 2, 3, 4, 5, 1, 2, 2, 3, 4]

a.uniq.each do |i|

?> puts i.to_s + ' has appeared ' + a.count(i).to_s + ' times'

end

1 has appeared 2 times

2 has appeared 3 times

3 has appeared 2 times

4 has appeared 2 times

5 has appeared 1 times

=> [1, 2, 3, 4, 5]