[英]How to remove all the rows from a matrix that match values in another vector?
I am making an exclude
vector, so that the rows containing any value present in the second column of the matrix user
from the exclude
list are removed. 我正在制作一个
exclude
向量,以便从exclude
列表中删除包含矩阵user
第二列中存在的任何值的行。 How do I do that efficiently, without using a for
loop to iterate through user
for each item in exclude
one by one? 我如何有效地做到这一点,而又不使用
for
循环逐一地逐个exclude
每个项目的user
?
My code below does not work: 我的以下代码不起作用:
count=0;
% Just showing how I am constructing `exclude`, to show that it can be long.
% So, manually removing each item from `exclude` is not an option.
% And using a for loop to iterate through each element in `exclude` can be inefficient.
for b=1:size(user_cat,1)
if user_cat(b,4)==0
count=count+1;
exclude(count,1) = user_cat(b,1);
end
end
% This is the important line of focus. You can ignore the previous parts.
user = user(user(:,2)~=exclude(:),:);
The last line gives the following error: 最后一行给出以下错误:
Error using
~=
使用
~=
出错
Matrix dimensions must agree.矩阵尺寸必须一致。
So, I am having to use this instead: 所以,我不得不改用这个:
for b=1:size(exclude,1)
user = user(user(:,2)~=exclude(b,1),:);
end
Example: 例:
user=[1433100000.00000 26 620260 7 1433100000000.00 0 0 2 1 100880 290 23
1433100000.00000 26 620260 7 1433100000000.00 0 0 2 1 100880 290 23
1433100000.00000 25 620160 7 1433100000000.00 0 0 2 1 100880 7274 22
1433100000.00000 21 619910 7 1433100000000.00 24.1190000000000 120.670000000000 2 0 100880 53871 21
1433100000.00000 19 620040 7 1433100000000.00 24.1190000000000 120.670000000000 2 0 100880 22466 21
1433100000.00000 28 619030 7 1433100000000.00 24.6200000000000 120.810000000000 2 0 100880 179960 16
1433100000.00000 28 619630 7 1433100000000.00 24.6200000000000 120.810000000000 2 0 100880 88510 16
1433100000.00000 28 619790 7 1433100000000.00 24.6200000000000 120.810000000000 2 0 100880 12696 16
1433100000.00000 7 36582000 7 1433100000000.00 0 0 2 0 100880 33677 14
1433000000.00000 24 620010 7 1433000000000.00 0 0 2 1 100880 3465 14
1433000000.00000 4 36581000 7 1433000000000.00 0 0 2 0 100880 27809 12
1433000000.00000 20 619960 7 1433000000000.00 0 0 2 1 100880 860 11
1433000000.00000 30 619760 7 1433000000000.00 25.0060000000000 121.510000000000 2 0 100880 34706 10
1433000000.00000 33 619910 7 1433000000000.00 0 0 2 0 100880 15060 9
1433000000.00000 26 619740 6 1433000000000.00 0 0 2 0 100880 52514 8
1433000000.00000 18 619900 6 1433000000000.00 0 0 2 0 100880 21696 8
1433000000.00000 16 619850 6 1433000000000.00 24.9910000000000 121.470000000000 2 0 100880 10505 1
1433000000.00000 16 619880 6 1433000000000.00 24.9910000000000 121.470000000000 2 0 100880 1153 1
1433000000.00000 28 619120 6 1433000000000.00 0 0 2 0 100880 103980 24
1433000000.00000 21 619870 6 1433000000000.00 0 0 2 0 100880 1442 24];
exclude=[ 3
4
7
10
17
18
19
28
30
33 ];
Desired output: 所需的输出:
1433100000.00000 26 620260 7 1433100000000.00 0 0 2 1 100880 290 23
1433100000.00000 26 620260 7 1433100000000.00 0 0 2 1 100880 290 23
1433100000.00000 25 620160 7 1433100000000.00 0 0 2 1 100880 7274 22
1433100000.00000 21 619910 7 1433100000000.00 24.1190000000000 120.670000000000 2 0 100880 53871 21
1433000000.00000 24 620010 7 1433000000000.00 0 0 2 1 100880 3465 14
1433000000.00000 20 619960 7 1433000000000.00 0 0 2 1 100880 860 11
1433000000.00000 26 619740 6 1433000000000.00 0 0 2 0 100880 52514 8
1433000000.00000 16 619850 6 1433000000000.00 24.9910000000000 121.470000000000 2 0 100880 10505 1
1433000000.00000 16 619880 6 1433000000000.00 24.9910000000000 121.470000000000 2 0 100880 1153 1
1433000000.00000 21 619870 6 1433000000000.00 0 0 2 0 100880 1442 24
Use ismember
to find the indices of the second column of user
where elements of exclude
exist to get the indices of the rows to be removed. 使用
ismember
可以找到存在exclude
元素的user
第二列的索引,以获取要删除的行的索引。 Negate these row indices to get the row indices to be kept and use matrix indexing to keep these rows. 取反这些行索引以获得要保留的行索引,并使用矩阵索引保留这些行。
user = user(~ismember(user(:,2),exclude),:);
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