How can I count the largest number of repeated numbers in a double?

I have a double that is 5644x1 and it consists of nothing but 0's and 1's.

ex: 00000000101100000011110000110000

I want to count the longest length of repeated 0's in this double, which in the case of this example would be 8. Can you please help?

Answer 1

[John D'Errico]

First, this is NOT a double vector.

00000000101100000011110000110000

It might be a string. But if you tried to write that vector as a double, it would be just one number, in decimal form. So you might have it stored as a vector binary elements. I'll assume you have a character string, but the answer is trivially changed if not.

V = '00000000101100000011110000110000';

We are looking for the longest length of repeated 0's.

st10 = strfind(['1',V],'10') + 1;
st01 = strfind([V,'1'],'01');
st01 - st10 + 2
ans =
     8     1     6     4     4

So the length of the LONGEST such string of zeros is just...

max(st01 - st10 + 2)
ans =
     8

If your vector is actually a numeric vector, perhaps like this, strfind still works

V=[0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 0 0];
st10 = strfind([1,V],[1 0]) + 1;
st01 = strfind([V,1],[0 1]);
max(st01 - st10 + 2)
ans =
     8

[Jon Mick]

I apologize, it's not a string but a double that 5644x1. I put 00000111000 just to give a better example of what I am looking to accomplish.

[John D'Errico]

Then the second solution is what you want.

[Adam Danz]

I didn't know strfind() does that, too. Nice!

[John D'Errico]

I guess it is one of those features that date back to the dark ages of MATLAB, when there was sort of a duality beween strings and numeric integer vectors containing ASCII code values. The reason why you can still do things like this:

C = 'ABCDE';
+C % ascii code values
ans =
    65    66    67    68    69
    
C - 'A'
ans =
     0     1     2     3     4
    
N = '012345';
N - '0'
ans =
     0     1     2     3     4     5

[Adam Danz]

char([73 39 108 108 32 104 97 118 101 32 102 117 110 32 119 105 116 104 32 116 104 105 115 33])

Answer 2

[the cyclist]

I recommend downloading the RunLength utility from the File Exchange.

Answer 3

[Image Analyst]

You can use regionprops(), if you have the Image Processing Toolbox

signal = [0 0 0 0 0 0 0 0 1 0 1 1 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 0 0];
props = regionprops(logical(signal == 0), 'Area'); % Measure lengths of each run of zeros
longestStretch = max([props.Area])  % Find the length of the longest one.

You get:

longestStretch =

8

[Jon Mick]

This might work but I don't have the Image Processing Toolbox :(