How to simulate bit stuffing on a 20860×1 matrix of binary data?

Hello everyone,

i have a matrix of binary data of size 20860×1. (20860 rows and 1 column), and i would like to perform bit stuffing on it, which means to insert a zero after each six consecutive ones

so if i have a sequence like this in my matrix: 0 0 0 1 1 1 1 1 1 1 0

then after the bit stuffing it will be like this: 0 0 0 1 1 1 1 1 1 0 1 0

i tried doing this using two for loops but it didn't work properly

let the data matrix be called: collect, and let it be a matrix of random binary data

collect=randi([1 0],20860,1);

[Fangjun Jiang]

Does the six ones need to be consecutive?

[Rania Fahmy]

they do have to be consecutive yes

[Fangjun Jiang]

I can suggest utilizing sparse matrix, see sparse().

Answer 1

[Guillaume]

An easy way:

%demo array that will fail with most naive algorithms:
v = [ones(1, 8), 0, ones(1, 5), 0, ones(1, 20)]
newv = regexprep(char(v + '0'), '111111', '1111110') - '0'

[Rania Fahmy]

This does work sir, thank you!

Answer 2

[Omer Yasin Birey]

Hi Rania, you may try this:

a =randi([0 1],1,20860);
a = num2str(a);
a = strsplit(a);
a = strcat(a);
a = cell2mat(a);
k = strfind(a,'111111');

for i = 1:length(k)
    b = [a(1:k(i)+6) '0' a(k(i)+8:end)];
end

b = b';

[Guillaume]

I've not tried to fully understand what this answer is doing. I'll note that conversion to string (and back) is going to be slow.

At the very least, for a vector of 0 and 1, a conversion to string with:

a = randi([0 1], 1, 20860);
str = char(a + '0');

is going to be much faster than num2str.

Note that although undocumented strfind also works with vectors of numbers.

Also, I suspect that this answer will insert a 0 after the 6th, 7th and 8th one in a sequence of 8 consecutive 1.

edit: actually, it would do if the loop wasn't completely broken. As it is, it just insert a 0 at the end of the last sequence no matter how many there are.

[Rania Fahmy]

I just tried this, and it gives me the same original matrix. For some reason it just didn't add any zeros after the occurance of 6 consecutive ones.