Delete rows when a value repeated less than 5 times
7 次查看(过去 30 天)
显示 更早的评论
I have a matrix:
a b c
1 201 1
2 202 1
3 203 1
4 204 1
5 205 1
6 206 1
7 207 2
8 208 2
9 209 2
10 210 2
11 222 3
12 232 3
I would like to remove rows 7-12 which have a value in the last column (c) repeated less than 5 times. Any help is appreciated.
0 个评论
采纳的回答
Sean de Wolski
2017-8-31
编辑:Sean de Wolski
2017-8-31
m = [1 201 1
2 202 1
3 203 1
4 204 1
5 205 1
6 206 1
7 207 2
8 208 2
9 209 2
10 210 2
11 222 3
12 232 3];
% Unique elements and locations in third column
[uv, ~, id] = unique(m(:,3));
% How many of each?
n = histcounts(id);
% Keep ones with more than 5.
m2 = m(ismember(m(:,3), uv(n>=5)),:)
2 个评论
Karena Weduwen
2018-3-19
编辑:Karena Weduwen
2018-3-19
Hello Sean, your code works perfectly fine on a small testfile I use (190 rows).
But as soon as I add some more rows, the
n = histcounts(id);
part starts giving weird values. I cannot find the reason for that change.
Attached you find the two files:
working.txt code runs through without any trouble
not working.txt "n = histcounts(id);" gives strange output and the m2 stays empty.
Any suggestions on how the code could be adjusted to work on a bigger file?
since my file looks a little different (I am searching in the first column) here is the code I use:
if true
load working.txt
a = working(:,:);
[uv, ~, id] = unique(a(:,1));
n = histcounts(id);
m2 = a(ismember(a (:,1), uv(n==4)),:);
end
另请参阅
类别
在 Help Center 和 File Exchange 中查找有关 Structures 的更多信息
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!