count the number of transitions from 0 to 3 in cells in cell array

Question

merialu 2018-11-13

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https://ww2.mathworks.cn/matlabcentral/answers/429559-count-the-number-of-transitions-from-0-to-3-in-cells-in-cell-array

编辑： merialu 2018-11-13

Hi.

I have a cell array containing 1000 cells. in each cell there is a matrix with different number of rows but with 50 columns.

the rows contains number from 0-3. I want to count how many times a 0 is followed by a 3 in each column.

Below you can see the code that I used to count the total number of transitions, from any number to another. Is there an easy way to change this code so that it counts the number of transitions from a certain number to another?

x=numel(CA)
newCA=cell(x,1);
for i=1:x
     newCA{i}=sum(diff(CA{i})~=0);   
end

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Answer 1

Stephen23 2018-11-13

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https://ww2.mathworks.cn/matlabcentral/answers/429559-count-the-number-of-transitions-from-0-to-3-in-cells-in-cell-array#answer_346672

编辑：Stephen23 2018-11-13

Here is a simple method based on logcal arrays, demonstrated on two Nx4 matrices in a cell array. The first matrix has two 0,3 transitions, the second matrix has three.

>> C = {[0,1,2,3;0,3,0,3;0,2,0,1],[0,3,1,2;3,2,1,0;3,0,3,0;3,0,3,3]};
>> C{:}
ans =
   0   1   2   3
   0   3   0   3
   0   2   0   1
ans =
   0   3   1   2
   3   2   1   0
   3   0   3   0
   3   0   3   3
>> F = @(m) nnz(m(:,1:end-1)==0 & m(:,2:end)==3);
>> V = cellfun(F,C)
V =
   2   3
>> N = sum(V)
N =  5

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Stephen23 2018-11-13

>> C = {[0,0,0,0;3,1,2,0;0,0,3,1;3,3,0,1],[1,1,0,3;0,3,3,3;3,3,3,0]};
>> C{:}
ans =
   0   0   0   0
   3   1   2   0
   0   0   3   1
   3   3   0   1
ans =
   1   1   0   3
   0   3   3   3
   3   3   3   0
>> F = @(m) sum(m(1:end-1,:)==0 & m(2:end,:)==3, 1);
>> D = cellfun(F,C,'uni',0);
>> M = vertcat(D{:}) %  for each matrix
M =
   2   1   0   0
   1   0   1   0
>> sum(M,1)          % for all matrices
ans =
   3   1   1   0