MATLAB: How to exclude rows on the basis of specific entries

excluding rowsfiltermatrices

I have 260 rows and 16 columns with entries belong to {1,2,3,4}, I want to exclude those rows in which first four entries of each row is 4 , or in general how can I exclude rows on the basis of entries?

Best Answer

It's not clear what you mean by repeat.

If you mean you want to delete rows whose first four columns contain more than one 4:

A = [4 4 1 2; 4 4 4 4;1 4 2 4;4 2 3 2] 
todelete = sum(A(:, 1:4) == 4, 2) > 1;  
A(todelete, :) = []

If you mean you want to delete rows whose first four columns contain two more more consecutive 4, then it's a lot more complicated. One possible way

A = [4 4 1 2; 4 4 4 4;1 4 2 4;4 2 3 2] 
todelete = cellfun(@(row) ~isempty(strfind(row, [1 1])), num2cell(A(:, 1:4) == 4, 2));
A(todelete, :) = []

Related Solutions

MATLAB: Combine 2 column matrix into 1 column matrix

If you want to merge non-zero elements of the last column into the first column, then you can use this:

A = [1.0, 2.0, 3.0, 4.0, 0;...
     1.1, 2.1, 3.1, 4.1, 0;...
     1.2, 2.2, 3.2, 4.2, 0;...
     0,   2.3, 3.3, 4.3, 0;...
     0,   2.4, 3.4, 4.4, 0;...
     0,   2.5, 3.5, 4.5, 1.5;...
     0,   2.6, 3.6, 4.6, 1.6];
X = A(:,end)>0;
A(X,1) = A(X,end);
A(:,end) = [];

This gives A as

A =
    1.0    2.0    3.0    4.0
    1.1    2.1    3.1    4.1
    1.2    2.2    3.2    4.2
    0      2.3    3.3    4.3
    0      2.4    3.4    4.4
    1.5    2.5    3.5    4.5
    1.6    2.6    3.6    4.6

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: Combine 2 column matrix into 1 column matrix

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

Related Question