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. How do I do that efficiently, without using a for loop to iterate through user for each item in exclude one by one?
我正在创建一个排除向量，以便删除包含排除列表中矩阵用户的第二列中的任何值的行。如何有效地执行此操作，而不使用for循环来逐个遍历用户，逐个排除每个项目？
My code below does not work:
我的代码不起作用：
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
~=
Matrix dimensions must agree.使用〜=矩阵尺寸时出错必须同意。
So, I am having to use this instead:
所以，我不得不使用它：
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:
期望的输出：
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
1 个解决方案
#1
2
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. Negate these row indices to get the row indices to be kept and use matrix indexing to keep these rows.
使用ismember查找用户的第二列的索引，其中存在排除元素以获取要删除的行的索引。取消这些行索引以获取要保留的行索引，并使用矩阵索引来保留这些行。
user = user(~ismember(user(:,2),exclude),:);
#1
2
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. Negate these row indices to get the row indices to be kept and use matrix indexing to keep these rows.
使用ismember查找用户的第二列的索引，其中存在排除元素以获取要删除的行的索引。取消这些行索引以获取要保留的行索引，并使用矩阵索引来保留这些行。
user = user(~ismember(user(:,2),exclude),:);