Find the longest streak of 1's from a vector
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Suppose I have a vector of 0's and 1's. How can I find, without for-loop(s), the longest streak of 1's in that vector?
eg. For the vector v=[0,1,0,0,1,1,0,0, 1,1,1,1,1 ,0,1,0,1], I want codes that return: longest streak=5, location=9 .
Any suggestion? Thanks in advance.
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Guillaume
on 27 Nov 2014
I'm sure if you search cody you'll find a few of this type of problem. A combination of diff and find should do the trick. For example,
v=[0,1,0,0,1,1,0,0, 1,1,1,1,1 ,0,1,0,1];
vd = diff([0 v 0]); %the 0s ensure that there's always a pair of [+1 -1] in the diff
starts = find(vd == 1);
ends = find(vd == -1);
[longest_streak, idx] = max(ends-starts);
location = starts(idx);
2 Comments
Image Analyst
on 27 Nov 2014
Vic, you can also do it with regionprops() in the Image Processing Toolbox as an alternate method. Not sure it would be any fewer lines of code though.
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