Finding the number of consecutive points in a given vector, using a condition

suppose i have a vector A=[0.2, 0.3, 4,5,6,7,0.2,0.4,0.5,0.3];

I have to find all those points which are less than 1, and occur consecutively more than 3 times.

ie. for the given vector A, i would get [0.2,0.4,0.5,0.3]

kindly help me write a general code for say, A being n x 1 vector, find all those points which are less than x, and occur consecutively more than y times.

Answer 1

[Andrei Bobrov]

with function regionprops from Image Processing Toolbox

idx = regionprops(A<1,'Area','PixelIdxList');
out = cellfun(@(x)A(x),{idx([idx.Area] > 3).PixelIdxList},'un',0);

other way

t = A<1;
z = [find([true,diff(t)~=0]) numel(A)+1];
idx = [z(1:end-1);z(2:end)-1];
i1 = idx(:,t(idx(1,:)));
i2 = i1(:,(diff(i1) + 1) > 3);
out = arrayfun(@(x)A(i2(1,x):i2(2,x)),1:size(i2,2),'un',0);

third way

t = A<1;
t1 = [~t(1) t ~t(end)];
idx = [strfind(t1,[0 1]);strfind(t1,[1 0])-1];
i1 = idx(:,diff(idx) + 1 > 3);
out = arrayfun(@(x)A(i2(1,x):i2(2,x)),1:size(i2,2),'un',0);

[Vishesh Vatsal]

fantastic,thanks a lot!

just a comment: the first one doesn't work for say A=[0.2, 0.3, 4,5,6,7,0.2,0.4,0.5,0.3,3,2,1,0.1,0.1,0.1,0.1];

[Andrei Bobrov]

Hi Vishesh! I was corrected this is answer.