MATLAB Code for Huffman Encoding and Decoding

MATLAB Script

% The code is developed by SalimWireless.com
clc; clear; close all;

% INPUT TEXT
input_text = 'www.salimwireless.com';

% STEP 1: Source Statistics — Get unique symbols and probabilities
[unique_symbol, probability] = source_statistics(input_text);

% STEP 2: Huffman Encoding — Generate code words for each symbol
code_word = huffman_encoding(probability);

% STEP 3: Encode Text to Bit Stream
bit_stream = [];
for i = 1:length(input_text)
    index = find(unique_symbol == input_text(i));
    bit_stream = [bit_stream code_word{index}];
end
bit_stream = bit_stream - '0';  % Convert to numeric

% STEP 4: Decode Bit Stream to Text
decoded_msg = huffman_decoding(unique_symbol, code_word, bit_stream);

% OUTPUT
disp('Original Message:');
disp(input_text);
disp('Encoded Bit Stream:');
disp(num2str(bit_stream));
disp('Decoded Message:');
disp(decoded_msg);

% STEP 5: Visualization
figure;

% Plot symbol probabilities
subplot(2, 1, 1);
bar(probability, 'FaceColor', [0.2 0.6 0.5]);
set(gca, 'xticklabel', cellstr(unique_symbol'), 'xtick', 1:length(unique_symbol));
title('Symbol Probabilities');
xlabel('Symbols');
ylabel('Probability');
grid on;

% Plot code word lengths
code_lengths = cellfun(@length, code_word);
subplot(2, 1, 2);
bar(code_lengths, 'FaceColor', [0.3 0.4 0.8]);
set(gca, 'xticklabel', cellstr(unique_symbol'), 'xtick', 1:length(unique_symbol));
title('Huffman Code Word Lengths');
xlabel('Symbols');
ylabel('Code Length (bits)');
grid on;

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%%%                        Supporting Functions                         %%%
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

function [unique_symbol, probability] = source_statistics(text)
    unique_symbol = unique(text); 
    count_symbol = histc(text, unique_symbol);
    probability = count_symbol / length(text); 
    [probability, index] = sort(probability, 'descend'); 
    unique_symbol = unique_symbol(index);
end

function code_word = huffman_encoding(prob)
    n = length(prob); 
    code_word = cell(1, n);
    prob = fliplr(prob);  % ascending

if n == 1
        code_word{1} = '1'; 
        return;
    end

x = zeros(n, n); 
    x(:, 1) = (1:n)';

for i = 1:n-1
        temp = prob; 
        [~, min1] = min(temp);  
        temp(min1) = 1; 
        [~, min2] = min(temp); 
        prob(min1) = prob(min1) + prob(min2); 
        prob(min2) = 1; 
        x(:, i+1) = x(:, i); 
        for j = 1:n
            if x(j, i+1) == min1
                code_word{j} = strcat('0', code_word{j}); 
            elseif x(j, i+1) == min2
                x(j, i+1) = min1; 
                code_word{j} = strcat('1', code_word{j});
            end
        end
    end
    code_word = fliplr(code_word); 
end

function decoded_msg = huffman_decoding(unique_symbol, code_word, bit_stream)
    decoded_msg = ''; 
    i_min = min(cellfun(@length, code_word));
    ptr = 1; 
    for i = i_min:length(bit_stream)
        temp_code = char(bit_stream(ptr:i) + '0');
        match_idx = find(strcmp(code_word, temp_code), 1);
        if ~isempty(match_idx)
            decoded_msg = [decoded_msg, unique_symbol(match_idx)];
            ptr = i + 1;
            i = i + i_min;
        end
    end
end
web('https://www.salimwireless.com/search?q=huffman%20encoding%20decoding', '-browser');

Output

Original Message:

www.salimwireless.com

Encoded Bit Stream:

0 1 0 1 0 1 1 0 0 1 0 1 1 1 0 1 1 1 1 1 1 0 0 0 1 1 1 0 0 1 0 0 0 1 1 0 0 0 0 0 1 1 1 1 1 0 0 1 1 0 1 1 0 1 1 0 0 1 1 0 1 0 1 1 0 0 1 1 1 1 0

Decoded Message:

www.salimwireless.com

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