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How to find an exact sequence of values?

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Pete
Pete on 29 Nov 2019
Answered: Image Analyst on 3 Dec 2019
Hi everyone,
as the title says I'm looking to find an exact sequence of values in a matrix. I have a matrix that I'm turning into a logical array as below. Now I want to be able to say if the consecutive ones in the column are less than X (as in e - see below) they should also be turned into zeroes as well.
I tried to work with find(contain()) but that did nothing. Also ismember() did not turn out the results I was looking for.
Turning matrix into binary representation
for k = 1:1:size(p,1)
for l = 1:1:(size(p,2))
if p(k,l) > z
p(k,l) = 1;
else
p(k,l) = 0;
end
end
end
Logical array
0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0
0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0
0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0
0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0
0 0 1 0 1 1 1 1 0 0 0 0 0 0 0 0
0 0 1 0 1 1 1 0 0 0 0 1 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 1 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 1 0 0 0
0 0 0 0 1 0 0 0 0 0 0 0 1 1 0 0
0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 1
Size of ones I would like to be able to filter
e = ones(x,1)
Thank you for your help everyone! It's greatly appreciated.
Cheers,
Peter

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Pete
Pete on 2 Dec 2019
Hey everyone,
thank you for the answers, unfortunately I've been unable to apply RunLength to my problem and if I use regexp() search I cannot enter something along the lines of ones(x,1) and then
x = [1 2 3 4 5];
I'm very new to all of this so I'm probably not doing it right but is there anything else you might be able to recommend?
Thank you for your help!!
dpb
dpb on 2 Dec 2019
Show us what you tried with runlength -- can't imagine it would not work to do the job...and actually, what regexp pattern you used. I'm no whizard on regular expressions but there are those here who are.
Pete
Pete on 3 Dec 2019
Luna's approach worked very well. Thank you for your input everyone!

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Accepted Answer

Luna
Luna on 2 Dec 2019
Edited: Luna on 2 Dec 2019
Try Loren's findpattern2. Here is link:
create vector x numbers of ones and run findpattern2.
e = ones(1,x);
for i = 1:size(LogicalArray,2)
indices = findpattern2(LogicalArray(:,i),e);
if ~isempty(indices) % if it finds x elements of this pattern make them zero.
for k=1:numel(indices)
LogicalArray(indices(k):indices(k)+x,i) = false; % from indice to pattern length will be zero
end
end
end

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Pete
Pete on 3 Dec 2019
That worked perfectly! Thank you

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More Answers (1)

Image Analyst
Image Analyst on 3 Dec 2019
If you want to use functions already built in to the toolbox, you can use bwareafilt:
binaryImage = logical([...
0 0 1 0 0 0 0 0 0 0 0 0 0 0 0 0
0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 1 1 1 0 0 0 0 0 0 0 0 0
0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0
0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0
0 0 1 0 1 1 1 1 0 0 0 0 0 0 0 0
0 0 1 0 1 1 1 0 0 0 0 1 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 0 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 0 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 1 0 0 0
0 0 1 0 1 0 0 0 0 0 0 1 1 0 0 0
0 0 0 0 1 0 0 0 0 0 0 0 1 1 0 0
0 0 0 0 1 0 0 0 0 0 0 0 1 0 0 0
0 0 0 0 1 0 0 0 0 0 1 0 0 0 0 1])
x = 4; % Whatever....
% Get rid of stretches of 1's in each row that are less than x long.
for row = 1 : size(binaryImage, 1)
binaryImage(row, :) = bwareafilt(binaryImage(row, :), [x, inf]);
end
The result is:
binaryImage =
17×16 logical array
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0
0 0 0 1 1 1 1 0 0 0 0 0 0 0 0 0
0 0 0 0 1 1 1 1 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

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