Find 625 consecutive ones in vector

Hello,

I have a 45000x1 rowvector, which contains only 1's and 0's. I want to find the periods of 625 consecutive ones and locations of these 1's in this vector. Can anyone help?

Thank you.

[Sean de Wolski]

Exactly 625 or >=625?

[John D'Errico]

As Sean points out, the difference might change how one solves the problem. Do you want to find ALL occurrences of exactly 625 ones? What if there is a string of length 626? Does that correspond to two sustrings of length 625, one starting one element further down the line? Or is that just one string, that happens to satisfy the goal? What if there was a string of length 1250? Is that two consecutive strings of length 625? Or is it 625 strings of length 625 that overlap, or is it just one string?

Answer 1

[Ameer Hamza]

See strfind: https://www.mathworks.com/help/matlab/ref/strfind.html

The following code will find 3 consecutive ones in an input array and output the starting index of each occurrence

x = [0 1 1 1 0 0 1 1 0 1 1 1 0 1];
index = strfind(x, [1 1 1]);

output

index =
     2    10