Question

Say I have an array that looks like:

a = [cat, dog, cat, mouse, rat, dog, cat]

How do I cycle through that, and do something with duplicates – e.g. say delete them?

In other words, if I did a.each do |i|, how do I evaluate a[0], against a[1], a[2], a[3]…and then when I find the one I want, say a[2] in this case has the first duplicate, I then push it to a stack or remove it or something.

I know how to evaluate keys, versus values…but how do I evaluate values against each other within the same array?

Thanks.

Answer 1

You can create a hash to store number of times any element is repeated. Thus iterating over array just once.

h = Hash.new(0)
['a','b','b','c'].each{ |e| h[e] += 1 }

Should result

 {"a"=>1, "b"=>2, "c"=>1}