Truncating vector to longest continuous string of numbers

I have a number of 10000x1 arrays with some bad data and only want to keep the longest continuous part of the array. I have spent quite a while searching but cannot find an answer.

So what I am looking for is a way for MATLAB to search each vector, find the longest continuous set of numbers above a certain value and discard the rest. This should be simple but I cannot found and easy solution.

eg m = [1,2,3,4,5,6,-5,-5,-5,1,2,3,4,5,6,7,-5,-5,-5,-5,1,2,3,4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]; would return m=[ 1,1,1,1,1,1,1,1,1,1,1,1,1,1,1 ]

Thanks

EDIT the array is not necessarily continuous numbers.

[dpb]

<Previous?> has several answers plus there's a submittal on File Exchange on finding runs--I forget the exact name but a search should uncover it...

Answer 1

[Andrei Bobrov]

m=[ 1 2 3 4 5 6 -5 -5 -5 1 2 3 4 5 6 7 -5 -5 -5 -5 1 2 3 4];

z = diff(m) == 1;
z = [z(1);z(:)];
z(diff(z)==1) = 1;
a = zeros(numel(z),1);
a(diff([0;z]) == 1) = 1;
a = cumsum(a,1).*z;
n = accumarray(a+1,1);
[~,ii] = max(n(2:end));
out = m(a == ii);

or

z = diff(m) == 1;
z = [z(1),z(:)'];
z(strfind(z,[0 1])) = 1;
a = regionprops(z,'Area','PixelIdxList');
out = m(a([a.Area] == max([a.Area])).PixelIdxList);

[nickname1]

Thanks very much for your help but it is the same as the comment below. The numbers in my array are not consecutive hence if my array is m = [1,2,3,4,5,6,-5,-5,-5,1,2,3,4,5,6,7,-5,-5,-5,-5,1,2,3,4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]; your code pulls out 1 2 3 4 5 6 7 not the string of ones. thanks

Answer 2

[Stephen23]

>> m = [1,2,3,4,5,6,-5,-5,-5,1,2,3,4,5,6,7,-5,-5,-5,-5,1,2,3,4];
>> d = diff([false,diff(m)==1,false]);
>> vb = find(d>0);
>> ve = find(d<0);
>> [~,idx] = max(ve-vb) % which sequence is the longest
idx = 2
>> m(vb(idx):ve(idx)) % get that sequence
ans =
   1   2   3   4   5   6   7

[nickname1]

Thanks but I missed something when writing my question. The numbers in the array are not consecutive hence if my array is m = [1,2,3,4,5,6,-5,-5,-5,1,2,3,4,5,6,7,-5,-5,-5,-5,1,2,3,4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1]; your code pulls out 1 2 3 4 5 6 7 not the string of ones. thanks though it gives me something to work on.

[Stephen23]

@nickname1: so what you want is the longest sequence of positive values? Like this?:

>> m = [1,2,3,4,5,6,-5,-5,-5,1,2,3,4,5,6,7,-5,-5,-5,-5,1,2,3,4,1,1,1,1,1,1,1,1,1,1,1,1,1,1,1];
>> d = diff([false,m>0,false]);
>> vb = find(d>0);
>> ve = find(d<0)-1;
>> [~,idx] = max(ve-vb) % which sequence is the longest
idx = 3
>> m(vb(idx):ve(idx)) % get that sequence
ans =
   1   2   3   4   1   1   1   1   1   1   1   1   1   1   1   1   1   1   1