Finding a specific pattern in data
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Hello all,
I would like to create a routine to identity if a specifi pattern exists in may data.
So far I did this:
data=somematrix;
% Define the pattern to search for
pattern = [3, 4, 5];
% Initialize a flag to check if the pattern is found
patternFound = false;
% Iterate through the data with a sliding window
for i = 1:(length(data) - length(pattern) + 1)
% Extract a subsequence of the same length as the pattern
subsequence = data(i:i+length(pattern)-1);
% Compare the subsequence with the pattern
if isequal(subsequence, pattern)
patternFound = true;
break; % Exit the loop if the pattern is found
end
end
% Display the result
if patternFound
disp('Pattern Found in the Data.');
else
disp('Pattern Not Found in the Data.');
end
This works when the data is a vector but is not working if instead a vector I'm working with a matrix.
Thanks in advance.
1 Comment
Dyuman Joshi
on 10 Nov 2023
How should the pattern be detected in the matrix?
Horizontally? Vertically? Diagonally? Or reverse of the orientations mentioned?
Answers (1)
Johnny
on 10 Nov 2023
Hello Ricardo,
You can use the ismember function (https://www.mathworks.com/help/matlab/ref/double.ismember.html) combined with logical operations.
patternFound = false ;
% Check if pattern is a subset of data
if size(data,2) < size(pattern,2)
% pattern cannot be found: column number in pattern is greater than column number in data
patternFound = false ;
elseif size(data,2) == size(pattern,2)
% Same number of column between pattern and data
patternFound = all(ismember(pattern, data, 'rows'));
else
% column number in data is greater than column number in pattern
% Extract submatrices from data, to have the same number of columns
% for comparison and loop through the different combinations.
for k = 1:(size(data,2)-size(pattern,2)+1)
patternFound = all(ismember(pattern, data(:, k:(k+size(pattern, 2)-1)), 'rows'));
if patternFound
break
end
end
end
%
if patternFound
disp('Pattern Found in the Data.');
else
disp('Pattern Not Found in the Data.');
end
6 Comments
Dyuman Joshi
on 15 Nov 2023
@Ricardo Duarte, see the below example -
arr = [3 4 6
4 4 6
5 6 5];
pattern = [3 4 5];
In the array, the pattern is found - but vertically and diagonally, which is not the same the orientation as of the pattern, that is horizontal.
So, here, should the pattern be considered to be found, or not?
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