Find the number of calls in Ruby code that have happened no times, just once, or many times.

zom.rb

require 'set'
require 'find'

class Array
  def to_h; Hash[self]; end
  def to_set; Set.new(self); end
  def freq; group_by {|e| e }.map {|k,v| [k,v.count] }.to_h; end
end

all_words = 
  Find.find(File.expand_path(ARGV[0]))
      .grep(/\.rb$/)
      .reject {|fn| fn =~ /_spec\.rb$/ }
      .map {|fn| IO.read(fn).scan(/\w+/) }
      .flatten

method_set = 
  all_words.each_cons(2)
           .select {|fst,_| fst == "def" }
           .map {|_,method_name| method_name }
           .to_set
              
non_decl_names = 
  all_words.each_cons(2)
           .reject {|fst,_| fst == "def" }
           .map {|_,name| name }

freqs = 
  non_decl_names.select {|t| method_set.include?(t) }
                .freq
                .values
                .freq

zeros = (method_set.to_a - non_decl_names.uniq).count
ones = freqs[1]
manys = freqs.values.reduce(:+) - ones
percentage = ones / (ones.to_f + manys) * 100.0

puts "zeros: #{zeros}\nones: #{ones}\nmanys: #{manys}\npercentage: #{percentage}"