How to find the find the pattern in each row of Matrix?

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Kazi Alam
Kazi Alam 2021-6-10
编辑： Adam Danz 2021-6-10
Hallo, Thanks for reading!
The array that I am working with consist of 8 column.
1 2 3 4 5 6 7 8
==========================================================
0 3.2 0 3.3 0 2 19 0
3.2 0 3.2 0 3.3 0 2 0
0 0 6.2 0 0 8 21 0
3.2 9 3.2 0 0 0 2 0
...
The goals is to find the column number which are non-zeros. For example: row1 = 2468, row2 = 1357, row3= 367 so on. With these I would like finally find out what is the most frequent pattern.
The current code is
for i=1:length(data)
k(i,:)= find(data(i,:)~=0);
end
However, my array is inconsistent how to solve this problem? Returning the following error:
Unable to perform assignment because the indices on the left side are not compatible with the size of the right side.

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采纳的回答

Kazi Alam
Kazi Alam 2021-6-10
编辑：Kazi Alam 2021-6-10
Already found a better option!
Here is the code.
for i=1:length(outerwall)
k(:,i)= str2double(sprintf('%d',find(outerwall(i,:)~=0)));
end
Edit:
for more info
https://de.mathworks.com/matlabcentral/answers/483625-how-to-combine-all-columns-of-an-array-into-one-column
  1 个评论
Adam Danz
Adam Danz 2021-6-10
编辑：Adam Danz 2021-6-10
This solution is bad for two reasons.
  1. Is very inefficient. It converts vectors to strings, then back to a numbers, and uses a loop, all of which can be avoided.
  2. Most importantly, this method will fail if there are more than 9 columns. Example: let's say the pattern in row j is [1 3] and the pattern in row k is [13]. That produces the same output "13" even though the 2 patterns have no overlap at all. Another example: what columns are represented by '123'? [1 2 3] or [1, 23] or [123]?
dpb's answer is much more efficient, cleaner, quicker, and robust.

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更多回答（1 个）

dpb
dpb 2021-6-10
A=[A;A(3,:)]; % make sure one row has same pattern
% the engine
B=(A~=0); % convert to logical array for pattern, independent of value
[~,ib]=ismember(B,unique(B,'rows'),'rows'); % locations of each pattern
N=histcounts(ib); % count number of each pattern located
For the above augmented, array, this returns
>> N
N =
2 1 1 1
>>
which shows the first row was duplicated; all rest were unique, only occurring once.

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