Ruby Alphabet Upcase : So i can print the alphabet in Ruby.

     alphabet = (a..z)

I can convert strings into Uppercase 

    string.upcase

However I can't figure out the right syntax to print the alphabet in uppercase. 

I have the below code, which maps a frequency count to the displayed alphabet, I just want to be able to have each letter on a separate line and in uppercase. 

    mappedfreq = alphabet.upcase.collect do | s1 |frq = @lt[s1]
    s1 + (frq> 0 ? ": #{'x ' x frq}" : '')

But placing the above ".upcase" throws an error. 

