How to calculate the entropy?

How can I calculate the entropy of a sentence and selected sentence of a string. Thanks

[darova]

Where is MATLAB?

Answer 1

[Ameer Hamza]

Suppose you have a string

str = 'A quick brown fox';

1. If you have image processing toolbox, then try

ent = entropy(uint8(str))

2. Otherwise, you can also download this FEX submission: https://www.mathworks.com/matlabcentral/fileexchange/38295-compute-the-entropy-of-an-entered-text-string

ent = ComputeEntropy(str);

3. You can also write the following code which does not require any other toolbox

p = sum(str.'==unique(str))./length(str);
ent = -sum(p.*log2(p));

Same result for all three options

ent =
    3.6901

[Balkar Singh]

Thanks Sir..

[Ameer Hamza]

Glad to be of help.

[Balkar Singh]

str = 'A quick brown fox. It can run fast';

Sir I want to calculate the entropy for both the sentences individually.

Thanks

[Ameer Hamza]

You can split the string into sentences using strsplit() and then calculate entropy

str = 'A quick brown fox. It can run fast';
sentences = strsplit(str, '.');
entropy_sentences = cellfun(@(x) entropy(uint8(x)), sentences)

[Balkar Singh]

Ok sir thanks

[Balkar Singh]

मैं भारत से प्यार करता हूँ |

गुरुदेव रवींद्र नाथ ठाकुर भारत के बँगला साहित्य के शिरोमणि कवि थे |

The above solution is not working for this language(Hindi). I want to embed entropy of first sentence after first sentence and entropy of second sentence after second sentence.

Thanks

[Ameer Hamza]

Something like this?

str = 'मैं भारत से प्यार करता हूँ | गुरुदेव रवींद्र नाथ ठाकुर भारत के बँगला साहित्य के शिरोमणि कवि थे |';

sentences = strsplit(str, '|');
sentences = sentences(~(cellfun(@(x) isempty(x), sentences)));
entropy_sentences = cellfun(@(x) {num2str(entropy(uint8(x)))}, sentences);

comb_vec = cell(1, numel(sentences)*2);
comb_vec(1:2:end) = sentences;
comb_vec(2:2:end) = entropy_sentences;

strjoin(comb_vec, '')

[Balkar Singh]

Thanks sir.

[Balkar Singh]

s = struct('zero', {strcat(char(8206),char(8206))},'one',{strcat(char(8206),char(8236))},'two',{strcat(char(8206),char(8237))},'three',{strcat(char(8206),char(8204))},'four',{strcat(char(8204),char(8206))},'five',{strcat(char(8204),char(8236))},'six',{strcat(char(8204),char(8237))},'seven',{strcat(char(8236),char(8236))},'eight',{strcat(char(8236),char(8204))},'nine',{strcat(char(8236),char(8237))},'dot', {strcat(char(8204),char(8204))});

final = ' ';

for i =1:size(entropy_sentences,2)

val_final='';

ent = (entropy_sentences(1,i))

input('check')

for j = 1:size(ent,2)

if(isequal(ent(1,j),0))

val = getfield(s,'zero')

input('check 0 ');

elseif(isequal(ent(1,j),1))

val = getfield(s,'one')

elseif(isequal(ent(1,j),2))

val = getfield(s,'two')

elseif(isequal(ent(1,j),3))

val = getfield(s,'three')

elseif(isequal(ent(1,j),4))

val = getfield(s,'four')

input('check 4 ');

elseif(isequal(ent(1,j),5))

val = getfield(s,'five')

elseif(isequal(ent(1,j),6))

val = getfield(s,'six')

elseif(isequal(ent(1,j),7))

val = getfield(s,'seven')

elseif(isequal(ent(1,j),8))

val = getfield(s,'eight')

elseif(isequal(ent(1,j),9))

val = getfield(s,'nine')

input('check 9');

elseif(isequal(ent(1,j),'.'))

val = getfield(s,'dot')

input('dot')

end

val_final = [val_final,val];

end

end

I tried this code to convert this entropy into Zero width code but its not working. There is any method to covert the entropy before embedding process.

[Ameer Hamza]

I am not sure clear about your question. Can you give more details or better it might be better to start a new question so that it will get more attention from others.

[Balkar Singh]

Ok sir, let me explain..

str = 'मैं भारत से प्यार करता हूँ | गुरुदेव रवींद्र नाथ ठाकुर भारत के बँगला साहित्य के शिरोमणि कवि थे |';

I sent you this string and asked how to calculate of this string.

then you replied with the following code.

sentences = strsplit(str, '|');

sentences = sentences(~(cellfun(@(x) isempty(x), sentences)));

entropy_sentences = cellfun(@(x) {num2str(entropy(uint8(x)))}, sentences);

comb_vec = cell(1, numel(sentences)*2);

comb_vec(1:2:end) = sentences;

comb_vec(2:2:end) = entropy_sentences;

strjoin(comb_vec, '')

I want to convert the entropy into Zero Width Characters before the embedding process.

Thanks sir.

[Ameer Hamza]

Do you want to replace entropy value with zero width character?

[Balkar Singh]

yes to make it invisible