stock_numbers.rb

# number of rows in the file
results.size
# => 105293

# number of unique stock ids
results.map {|l| l[:stock_unique_id]}.uniq.size
# => 95067  

# number of stocked lines
stocked_ids   = Set.new(results.select {|l| l[:stocked] == '1'}.map {|l| l[:stock_unique_id]})
stocked_ids.size
# => 26649 

# number of unstocked lines
unstocked_ids = Set.new(results.select {|l| l[:stocked] == '0'}.map {|l| l[:stock_unique_id]})
unstocked_ids.size
# => 68418

# no stock ids have both stocked and unstocked lines
stocked_ids.intersection(unstocked_ids).size
# => 0