This document contains code to count unique users from log data. It splits each line on commas, extracts the user ID, initializes a hash to count IDs, increments the count for existing IDs or initializes a new count, then prints the total number of unique users.

18. •

42. #!/usr/bin/ruby
ARGF.each do |line|
line.chomp!
logs = line.split(/,/)
unless logs.empty?
printf("%s,1n", logs[0])
end
end

43. #!/usr/bin/ruby
h = Hash.new
ARGF.each do |line|
line.chomp!
array = line.split(/,/)
uid = array[0]
c = array[1]
count = 1
if h.key? uid
count = h[uid].to_i + 1
end
h.store uid, count
end
printf("#{h.length}")