if statement does not execute the statements

Question

Maria445 2017-10-14

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/361311-if-statement-does-not-execute-the-statements

评论： Star Strider 2017-10-14

I can't understand what I'm doing wrong here; basically I have two matrices, A and B, and if one of the two matrices has a row in which every entry is equal to NaN, I want to delete the corresponding row in the other matrix as well. This is the code I used:

A1 = A;
B1 = B;
for i = 1 : size(A,1)
    if sum(isnan(A(i,2:end)))==size(A(:,2:end),2) || ...
            sum(isnan(B(i,2:end)))==size(B(:,2:end),2);
        A1(i,:) = []
        B1(i,:) = [];
    end
end

However, in matrix B1 there are still many rows entirely made of NaN values. Why is this not working?

1 个评论
显示 -1更早的评论隐藏 -1更早的评论

Maria445 2017-10-14

Also, every time I run the for loop again, matrices A1 and B1 reduce their dimension...this shouldn't happen

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Star Strider 2017-10-14

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/361311-if-statement-does-not-execute-the-statements#answer_285773

在 MATLAB Online 中打开

If I understand correctly what you want to do, this should work:

A = randi(9, 7, 4);                                         % Create Matrices
B = randi(9, 7, 4);                                         % Create Matrices
A([2 6],:) = NaN;                                           % Create ‘NaN’ Rows In ‘A’
B(4,:) = NaN;                                               % Create ‘NaN’ Rows In ‘B’
row_idx = all(isnan(A),2) | all(isnan(B),2);                % Logical Index For ‘NaN’ Rows In Both
A(row_idx,:) = [];                                          % Delete Rows In ‘A’
B(row_idx,:) = [];                                          % Delete Rows In ‘B’