逻辑索引而不是查找(logical indexing instead of find)

逻辑索引而不是查找(logical indexing instead of find)

我想改进一段代码

LaserS_P=rand(20,3); % duumy data LaserS_P(1:4:end,1)=0; index_= find( LaserS_P(:,1)); % finds o element in first row of 20*3 matrix. LaserS_P_new=LaserS_P(index_,:); % remove all rows (index_) from matrix

我如何在这种情况下使用逻辑索引。

I want to improve piece of code

LaserS_P=rand(20,3); % duumy data LaserS_P(1:4:end,1)=0; index_= find( LaserS_P(:,1)); % finds o element in first row of 20*3 matrix. LaserS_P_new=LaserS_P(index_,:); % remove all rows (index_) from matrix

How can i use logical indexing for this case.

最满意答案

要删除所有零值行（这不是您的示例所做的），您可以使用逻辑索引，如下所示：

LaserS_P=rand(20,3); % dummy data LaserS_P(1:4:end,1)=0; index_= ( LaserS_P(:,1) == 0); %# finds 0 element in first col of 20*3 matrix. %# index_ is a logical vector with ones wherever LaserS_P's first col is 0 LaserS_P_new=LaserS_P(~index_,:); %# remove all rows (index_) from matrix %# alternatively LaserS_P_new(index_,:) = []; %# remove all rows (index_) from matrix

To remove all the zero-valued rows (which is not what your example does), you can use logical indexing as follows:

LaserS_P=rand(20,3); % dummy data LaserS_P(1:4:end,1)=0; index_= ( LaserS_P(:,1) == 0); %# finds 0 element in first col of 20*3 matrix. %# index_ is a logical vector with ones wherever LaserS_P's first col is 0 LaserS_P_new=LaserS_P(~index_,:); %# remove all rows (index_) from matrix %# alternatively LaserS_P_new(index_,:) = []; %# remove all rows (index_) from matrix