How to remove zeros from end of different sizes of rows of matrix?

Hi,

Let say a result of array of different sizes of rwos:

                  array = 1 2 3 0 0

                          4 5 6 7 0 0

                          8 9 10 11 12 0

How to remove zeros from rows, so the array will be like this:

                  array = 1 2 3  

                          4 5 6 7  

                          8 9 10 11 12

[Jan]

It depends on what you want as output. Your

array = 1 2 3  
        4 5 6 7  
        8 9 10 11 12

does not reveal this detail, because this is no valid Matlab syntax. There are no such objects in Matlab. The most similar thing would be:

array = {[1 2 3], ...
         [4 5 6 7], ...
         [8 9 10 11 12]}

If you want this, Matt J's answer is a solution. If you want a "matrix" with a different number of columns per row, Rik's answer is correct: This is impossible.

So please explain exactly, what you want as output. Prefer to use valid Matlab syntax, which produces the objects, if the readers inserts them by copy&paste in Matlab's command window.

Answer 1

[Matt J]

                  array = {[1 2 3 0 0];
                          [4 5 6 7 0 0];
                          [8 9 10 11 12 0]};

fun=@(r) r(1:find(r,1,'last'));

arrayNoZeros=cellfun(fun, array, 'uni',0);

arrayNoZeros{:},

[Jan]

If a cell is wanted as output this works. Using a loop directly is faster than arrayfun with an expensive anonymous function:

n = size(X, 1);
Y = cell(n, 1);
for ix = 1:n
   r     = X(ix, :);
   Y{ix} = r(1:find(r, 1, 'last'));
end

This is about 8 times faster than arrayfun on R2016b for the input data:

X = randi([0, 3], 1000, 8);

Answer 2

[Rik]

This impossible with matrices in Matlab. What you can do is using a cell vector where each cell contains to trailing zeros.

Answer 3

[Star Strider]

It will not look like you want it to because numeric arrays must have the same number of columns in each row. The best you can do is convert it to a cell array, then eliminate the zero values. You will be able to use each row as a double array in subsequent calculations.

The Code —

array = [1 2 3 0 0 0
         4 5 6 7 0 0
         8 9 10 11 12 0];

carray = mat2cell(array, ones(1,size(array,1)), size(array,2));     % First, Create Cell Array
carray = arrayfun(@(x) x(x~=0), array, 'Uni',0);                    % Set ‘0’ To ‘[]’