This document is a MATLAB code that implements the Lempel-Ziv-Welch (LZW) lossless data compression algorithm. It takes an input message containing repetitive characters, encodes it using the LZW algorithm, and decodes the encoded output back to the original message. The code defines character sets, initializes dictionaries to map characters to numbers and vice versa, encodes the message by iterating through it and updating the dictionaries, and displays the encoded and decoded results.

1. Instituto Politécnico Nacional
Introducción a los Sistemas de Comunicación Seguros
Unidad MISTI Culhuacan
Presentado a: Dr. Gualberto Aguilar Torres
Algoritmo de comprensión
LZW
11
Por: Yango Alexander Colmenares
Fecha
Octubre de 2013
%% INSTITUTO POLITECNICO NACIONAL-MISTI CULHUACAN --- MEXICO DF 2013
%%Desarrollado por:Yango Colmenares
%Presentado a : Dr. Gualberto Aguilar Torres
%Programación en Matlab
%Codigo Lzw
clc;
clear all;
%%%SE ESTABLECEN CARACTERES VALIDOS Y COLUMNAS DE ASIGNACIÓN
llaves =
{'a','b','c','d','e','f','g','h','i','j','k','l','m','n','ñ','o','p','q',
'r','s','t','u','v','w','x','y','z'};
valores =
{1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27}
;
dicc = containers.Map(llaves, valores);
diccR = containers.Map(valores, llaves);
%%%MENSAJE A CODIFICAR CON PALABRAS REPETITIVAS CARACTERES ACEPTADOS POR
EL
%%%PROGRAMA
M = 'MIRAMESINMIRARMIRIAM';
M = lower(M);
M(ismember(M,' ,.:;!')) = [];
subcad = '';
outV = [];
for i=1:length(M)
subcad = strcat(subcad, M(i));
if ~isKey(dicc, subcad)
dicc(subcad) = length(dicc) + 1;
outV = [outV dicc(subcad(1:end - 1))];
subcad = subcad(end:end);
end
if i == length(M)

2. outV = [outV dicc(subcad)];
end
end
%%%MENSAJE A CODIFICAR CON SALIDA
disp('Resultado de la Codificación:');
disp(outV);
%%%MENSAJE A CODIFICAR CON SALIDA
dicc = containers.Map(llaves, valores);
subcad = '';
subV = [];
outC = '';
for i=1:length(outV)
subcad = strcat(subcad, diccR(outV(i)));
subV = [subV outV(i)];
subcadCell = repmat(subcad,length(subcad),1);
subcadCell = cellstr(char(subcadCell .*
tril(ones(length(subcadCell)))));
j = find(~dicc.isKey(subcadCell),1,'first');
if j > 0
dicc(subcadCell{j}) = length(dicc) + 1;
diccR(length(dicc)) = subcadCell{j};
subcad = diccR(subV(end:end));
outC = strcat(outC, diccR(subV(1:1)));
subV = subV(2:end);
end
if i == length(outV)
outC = strcat(outC, subcad);
end
end
disp('Decodificación:');
disp(outC);