[英]remove rows of matrix in matlab
If I have a matrix X
with only one column and it has some negative values in some rows. 如果我有一个只有一列的矩阵X
,并且在某些行中有一些负值。 How can I remove only the negative values? 如何仅删除负值?
Example: 例:
X=[-1; 2; 3; -4; 5]
should become: 应该变成:
X=[2; 3; 5]
Also, how can I remove values from 另外,如何从中删除值
y=[1; 2; 3; 4; 5]
based on where the negative values in X
are found? 基于X
中的负值的位置? y
should be [2; 3; 5]
y
应该是[2; 3; 5]
[2; 3; 5]
[2; 3; 5]
after this operation. [2; 3; 5]
。
Removing negative values from X
: 从X
移除负值:
You can either reassign X
to a vector which only contains the values of X
which are not negative: 您可以将X
重新分配给一个仅包含X
值不为负的向量:
>> X = X(X>=0)
X =
2
3
5
or delete the negative values from X
: 或从X
删除负值:
>> X(X<0) = []
X =
2
3
5
Removing values from y
based on the indices of negative values in X
is similar. 基于X
中负值的索引从y
删除值的过程类似。 Either reassign: 要么重新分配:
>> y = y(X>=0)
y =
2
3
5
Or delete: 或删除:
>> y(X<0) = []
y =
2
3
5
If you want to modify both vectors based on the negative values in X
remember to do the operation to y
first or store a logical vector for the positions where X<0
. 如果要基于X
的负值来修改两个向量,请记住首先进行y
运算或为X<0
的位置存储逻辑向量。 For example: 例如:
>> ind = X < 0;
>> X(ind) = []
X =
2
3
5
>> y(ind) = []
y =
2
3
5
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