MATLAB: How to decrease for loop variable counter when deleting rows in a matrix

arrayfor loopiterationMATLAB

I have an array A in which I delete rows based n a certain condition within another corresponding matrix which consists of the mean values of A. Each time I delete a row, I want my 'i' counter to jump back 1 iteration in order to not skip rows.

Means_Array=mean(A,2);
for i = 1:size(A,1)
       if Means_Array(i,1)==0
             Means_Array(i,:)=[];
             A(i,:)=[]; 
             i=i-1
     end
end

This does however not work for some reason and the 'i' resets back to the value it would have taken if the i=i-1 was not even there.

Best Answer

Just specify the for loop values to count downwards:

for i = size(A,1):-1:1
    ...
end

Related Solutions

MATLAB: Can this be done without a for loop

The following will put all elements above your threshold value to 0.

[row, col, index] = find( M > threshold);
M(index) = 0;

This next part will put the -1 at the first element like you want.

for i = 1:length(row)
    if(i > 1)
       if(row(i) < row(i-1))
          %the previous row was larger than the current row, break the loop
          break;
       end
    end
    %found the first element of the row that exceeds the threshold
    M(row(i),col(i)) = -1;
 end

Another option, is to do a loop and look at it row by row.

   [row, col] = size(M);
   for i = 1:row
       index = find(M(i,:) > threshold, 1);
   if(exists(index))
M(i,index) = -1;
   M(i,index+1:end) = zeros(1,col-index);
   end
   end

MATLAB: How to make a loop for all participants to delete rows that contain a certain value

Your loop does not seem to make any sense

Having a for loop such as

for j = 1:length(DATA(ii).GAIT_INFO);

means that j will take on values of 1, 2, 3.. up to what ever the termination condition is, in this case

length(DATA(ii).GAIT_INFO)

so j is just an integer. But then you have the statement

todelete = (j(:,1) == 1);

which makes no sense as why would you want to find out the locations where any row, column 1 of an integer equals one, which is what you are doing.

I think you also have some other problem with your termination condition itself.

length(DATA(ii).GAIT_INFO)

I think you probably want to do something like

for j = 3:size(filenames,1)
    A = DATA(j).GAIT_INFO;         
    todelete = A(:,1) == 1 ;
    A(todelete,:) = [];
    todelete= A(:,6) == 1;  
    A(todelete,:) = []; 
    DATA(j).GAIT_INFO = A
end

The above code could be cleaned up further, but I think this should give the idea

Best Answer

Related Solutions

MATLAB: Can this be done without a for loop

MATLAB: How to make a loop for all participants to delete rows that contain a certain value

Related Question