I need to replace an enitre row, if any of the value goes less than zero

Question

Suman 2015-2-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/179799-i-need-to-replace-an-enitre-row-if-any-of-the-value-goes-less-than-zero

编辑： Hikaru 2015-2-24

I need to check each row, whether is there any of the value less than zero in a particular row. If any value in a row is less than zero, i have to replace the entire row itself.

For example,

a1=[1 2; 3 4; -5 6] a2=[22 23; 56 78; 89 75]

Step 1: I need to check whether any element of a row is less than zero in matrix a1...... Step 2: If there is any negative value, i have to replace that particular row by the the same row of the another matrix a2.

Problem with the coding I did, If there is only one negative value in a row, then the negative value only is replaced by the another matrix of the same (row,column), but I couldn't replace the entire row.

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

Hikaru 2015-2-23

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/179799-i-need-to-replace-an-enitre-row-if-any-of-the-value-goes-less-than-zero#answer_168924

在 MATLAB Online 中打开

This will solve it.

    a1=[1 2; 3 4; -5 6]
    a2=[22 23; 56 78; 89 75]
    neg = a1<0 % return '1' for values less than zero
    a1(neg,:) = a2(neg,:) % step 2

4 个评论
显示 2更早的评论隐藏 2更早的评论

Stephen23 2015-2-23

编辑：Stephen23 2015-2-23

Are both of X and X_previous really the same size? Use the size command and tell us exactly what their sizes are.

This error arises because negative is referring to positions in one of the matrices that do not exist. Because negative is calculated from X, it is likely that X_previous is smaller than X, thus giving this error.

Hikaru 2015-2-24

编辑：Hikaru 2015-2-24

在 MATLAB Online 中打开

Now that I redo this problem with another matrix, the solution above does not work if the negative value is located in the second column.

Assuming you have matrix of 2 columns only, you might want to try the code below:

    neg1 = a1(:,1)<0
    neg2 = a1(:,2)<0
    neg = neg1|neg2
    a1(neg,:) = a2(neg,:)

I haven't fully tested it, but it should give you a start. Like Stephen said, you need to be more specific for a more specific solution.

请先登录，再进行评论。

I need to replace an enitre row, if any of the value goes less than zero

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

4 个评论
显示 2更早的评论隐藏 2更早的评论

更多回答（0 个）

另请参阅

类别

标签

Community Treasure Hunt

I need to replace an enitre row, if any of the value goes less than zero

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

采纳的回答

4 个评论 显示 2更早的评论隐藏 2更早的评论

更多回答（0 个）

另请参阅

类别

标签

Community Treasure Hunt

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

4 个评论
显示 2更早的评论隐藏 2更早的评论