Need to erease all the rows of a matrix where a zero appears

Question

Marco Boesso 2020-10-29

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/630578-need-to-erease-all-the-rows-of-a-matrix-where-a-zero-appears

评论： Marco Boesso 2020-10-29

采纳的回答： KSSV

Good evening folks (at least, here in Italy it's going to get dark very soon).

I need once more your help with a matrix manipulation. Let the matrix be:

A =

0 0 0

1 1 0

1 1 1

0 0 0

0 1 0

0 0 1

I need to erease all the rows where a null element appears. I.e., I want all the rows to go away minus the "1 1 1" row, so I just want one to survive. Notice that this is an hypothetical matrix, in reality, in my script, I don't know how many lines will be completely filled with ones and I want all of them to survive.

Thanks in advance.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

KSSV 2020-10-29

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/630578-need-to-erease-all-the-rows-of-a-matrix-where-a-zero-appears#answer_528223

在 MATLAB Online 中打开

A = [0     0     0
     0     0     0
     1     1     0
     1     1     1
     0     0     0
     0     1     0
     0     0     1] ; 
     
idx = all(A,2) ;
A = A(idx,:)
A = 1×3
     1     1     1

3 个评论
显示 1更早的评论隐藏 1更早的评论

Image Analyst 2020-10-29

编辑：Image Analyst 2020-10-29

在 MATLAB Online 中打开

Not dumb really - perfectly understandable misunderstanding that people make all the time. This is a perfect example of why one of my two main directives I give to people who code for me is to use descriptive variable names, even if they're longer, like indexes instead of idx. (The other one is to use tons of comments.) Below is how I was going to answer your question, before I saw you already got two other answers:

A = [0     0     0
     0     0     0
     1     1     0
     1     1     1
     0     0     0
     0     1     0
     0     0     1] ; 
% Find rows that have any non-zero values in them.     
rowsWithNonZeros = any(A, 2)
% Extract only those rows with at least one non-zero value in them.
A = A(rowsWithNonZeros, :)