CPSC 461: Copyright (C) 2003 Katrin Becker 1998-2002 Last Modified May 28, 2003 05:24 PM
LZW
"im a sheet slitter i slit sheets im the sleekest sheet slitter that ever slit sheets"
0 i 18 _s 36 hee 54 er_ 72  
1 m 19 sh 37 ets 55 _t 73  
2 _ 20 he 38 s_ 56 tha 74  
3 a 21 ee 39 _im 57 at 75  
4 s 22 et 40 m_t 58 t_e 76  
5 h 23 t_ 41 th 59 ev 77  
6 e 24 _sl 42 he_ 60 ve 78  
7 t 25 li 43 _sle 61 er_s 79
8 l 26 it 44 eek 62 sl 80  
9 r 27 tt 45 ke 63 lit_ 81  
10 k 28 te 46 es 64 _she 82  
11 v 29 er 47 st 65 eets 83  
12 eof 30 r_ 48 t_s 66   84  
13 clear 31 _i 49 she 67   85  
14 im 32 i_ 50 eet_ 68   86  
15 m_ 33 _sli 51 t_sl 69   87  
16 _a 34 it_ 52 lit 70   88  
17 a_ 35 _sh 53 tte 71   89  
 
CODE EMITTED: 0 1 2 3 2 4 5 6 6 7 18 8 0 7 7 6 9 2 0 24 26 18 20 22 4 31 15 7 20 24 21 10 6 4 23 19 21 48 25 27 29 2 41 3 23 6 11 54 4 52 35 50 4 12
Size of original file: 84 characters.
size of compressed file: 14 base codes plus 54 codes written =69 tokens total.
84 original bytes = 672 bits;
encoded 54 bytes = 432 bits
compression ratio = 0.65 (if we assume flattened case and no punctuation)
LZW The Code:
[1] Initialize string table;
[2] [current prefix] <- empty;
[3] K <- next character in charstream;
[4] Is [current prefix]K in string table?
"I.M.4.U..S.I.M..S.I.M..G.I.1.2.B.4.U.4.F.R.
U.R.X.T.C..S.U.R..S.U.R..I.N.10.2.B.4.U.4.F.R.
I.M.I.N.U..U.R.I.N.2..S.E.Z.2.C..B.B.
U.N.I.C.I.2.I..O..I.M.4.U..S.I.M..S.I.M.
U.N.I.L.B.S.1.4.F.R.N.F.R.N.F.R."
0 1 18 X 36 FR 54 INU 72 IO
1 2 19 Z 37 RU 55 UU 73 OI
2 4 20 eof 38 UR 56 URI 74 IM4
3 10 21 IM 39 RX 57 IN2 75 4US
4 B 22 M4 40 XT 58 2S 76 SIMS
5 C 23 4U 41 TC 59 SE 77 SIMU
6 E 24 US 42 CS 60 EZ 78 UNI
7 F 25 SI 43 SU 61 Z2 79 IL
8 G 26 IMS 44 URS 62 2C 80 LB
9 I 27 SIM 45 SUR 63 CB 81 BS
10 L 28 MG 46 RI 64 BB 82 S1
11 M 29 GI 47 IN 65 BU 83 14
12 N 30 I1 48 N10 66 UN 84 4FR
13 O 31 12 49 10.2 67 NI 85 RN
14 R 32 2B 50 2B4 68 IC 86 NF
15 S 33 B4 51 4U4F 69 CI 87 FRN
16 T 34 4U4 52 FRI 70 I2 88 NF
17 U 35 4F 53 IMI 71 2I 89  
CODE EMITTED:
9 11 2 17 15 21 25 11 8 9 0 1 4 23 2 7 14 17 14 18 16 5 15 38 43 14 9 12 3 32 34 36 21 47 17 38 47 1 15 6 19 1 5 4 4 17 12 9 5 1 9 13 21 23 27 27 66 9 10 4 15 0 35 14 12 36 12 36 20
"SO ALL WE COULD DO WAS TO SIT SIT SIT SIT
AND WE DID NOT LIKE IT NOT ONE LITTLE BIT"
0 A 18 _A 36 S_ 54 ID 72 LE
1 B 19 AL 37 _T 55 D_N 73 E_B
2 C 20 LL 38 TO 56 NO 74 BI
3 D 21 L_ 39 O_S 57 OT 75  
4 E 22 _W 40 SI 58 T_L 76  
5 I 23 WE 41 IT 59 LI 77  
6 K 24 E_ 42 T_ 60 IK 78  
7 L 25 _C 43 _S 61 KE 79  
8 N 26 CO 44 SIT 62 E_I 80  
9 O 27 OU 45 T_S 63 IT_N 81  
10 S 28 UL 46 SIT 64 NOT 82  
11 T 29 LD 47 _SI 65 T_O 83  
12 U 30 D_ 48 IT_ 66 ON 84  
13 W 31 _D 49 _AN 67 NE 85  
14 _ 32 DO 50 ND 68 E_L 86  
15 eof 33 O_W 51 D_W 69 LIT 87  
16 SO 34 WA 52 WE_ 70 TT 88  
17 O_ 35 AS 53 _DI 71 TL 89  
CODE EMITTED:
10 9 14 0 7 7 14 13 4 14 2 9 12 7 3 14 3 17 13 0 10 14 11 17 10 5 11 14 40 42 44 43 41 18 8 30 23 31 5 30 8 9 42 7 5 6 24 48 56 42 9 8 24 59 11 11 7 24 1 41 15
BackCPSC 461: Copyright (C) 2003 Katrin Becker 1998-2002 Last Modified May 28, 2003 05:24 PM