Generate a byte string of bits to show pass fail for a project

bit_magic.rb

projects = ['f','p','p','f','p','p','f','p','p','f']
bytes = []
projects.each_slice(4) do |chunk|
  byte = 0
  chunk.each{ |v| byte = (byte << 2) | (v == 'p' ? 1 : 2) }
  byte = byte << ((4 - chunk.size) * 2) if chunk.size < 4
  bytes << byte
  puts '%s %s %s' % [chunk, byte.chr, byte.chr.unpack("B*")]
end
byte_str = bytes.map{|b| b.chr }.join
bit_str = bytes.map{|b| b.chr.unpack("B*") }.join
puts byte_str
puts bit_str

out.txt

["f", "p", "p", "f"] � ["10010110"]
["p", "p", "f", "p"] Y ["01011001"]
["p", "f"] ` ["01100000"]
�Y`
100101100101100101100000