Error checking in a matrix

Question

Carsten 2014-12-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/165394-error-checking-in-a-matrix

评论： Carsten 2014-12-4

采纳的回答： Geoff Hayes

datafiltest.txt

在 MATLAB Online 中打开

I have the following code:

 [r , c] = size(m);
 if any(m(end,:)==-1)
     m(m<0) = 0;
 else
    for a=r-1:-1:1
        for b=1:c
            if m(a,b)==-1
                m(a,b)=m(a+1,b);
             end
        end
    end
 end

The code is checking if a matrix contains -1 in the last row. I have a couple of question regarding this code.It Works fine when checking from the last row to check for -1. If the is a -1 it replaces them all with zeros. If there are no -1 in the last row it locates the -1 and replace them with the value from the row that comes before. How do i do the opposite ? Check if the first row contains -1, and if so replace them with zeros. And if not then takes the value from the NeXT line and replace the -1 with that ?

Thanks a lot

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Answer 1

Geoff Hayes 2014-12-4

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/165394-error-checking-in-a-matrix#answer_161247

在 MATLAB Online 中打开

Carsten - just do something similar to what you have already, but opposite.

 [r, c] = size(m);
 if ~isempty(find(m(1,:)==-1))
     m(m==-1) = 0;
 else
    for a=2:1:r
        % get all indices of row a that correspond to elements
        % of negative one
        idcs = find(m(a,:)==-1);
        if ~isempty(idcs)
            m(a,idcs) = m(a-1,idcs);
        end
    end
 end