finding an item in an array
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Hello,
I have an array of five items for example 1 2 2 2 4
How can I find the positions of the repeated items, i.e 2 2 2?
Thanks
0 个评论
回答（7 个）
Aldin
2012-3-20
Here is my solution:
a = [ 1 2 2 2 4 ];
find(a==2)
ans =
2 3 4
2 个评论
Daniel Shub
2012-3-20
+1 for simplicity. While this requires knowing what number is repeated and will fail if multiple numbers are repeated, it does answer the question.
Aldin
2012-3-20
HERE IS THE COMBINATION OF Daniels AND my CODE:
x = [1 2 2 2 4 5 5 3 3 2];
a = unique(x);
[~,b] = unique(x, 'first');
[~,c] = unique(x, 'last');
ismember(x, a(b~=c))
the result will be: 0 1 1 1 0 1 1 1 1 1
(my code) if you want to get index:
find(ans==1)
result:
ans =
2 3 4 6 7 8 9 10
MURTADHA ALDEER
2012-3-20
0 个投票
1 个评论
Jonathan Sullivan
2012-3-20
Make sure you download the function. It is not built into MATLAB.
MURTADHA ALDEER
2012-3-20
0 个投票
3 个评论
Jonathan Sullivan
2012-3-20
There's a button in the top right that says "Download All." Click that one.
MURTADHA ALDEER
2012-3-22
Oleg Komarov
2012-3-25
Diret link to download: http://www.mathworks.com/matlabcentral/fileexchange/28113-findseq?controller=file_infos&download=true
FEX page for findseq: http://www.mathworks.com/matlabcentral/fileexchange/28113-findseq
Daniel Shub
2012-3-20
One of my uglier solutions ...
x = [1 2 2 2 4];
a = unique(x);
[~,b] = unique(x, 'first');
[~,c] = unique(x, 'last');
ismember(x, a(b~=c))
0 个评论
Aldin
2012-3-21
HERE IS THE COMBINATION OF Daniels AND my CODE:
x = [1 2 2 2 4 5 5 3 3 2];
a = unique(x);
[~,b] = unique(x, 'first');
[~,c] = unique(x, 'last');
ismember(x, a(b~=c))
the result will be: 0 1 1 1 0 1 1 1 1 1
(my code) if you want to get index:
find(ans==1)
result: ans = 2 3 4 6 7 8 9 10
0 个评论
MURTADHA ALDEER
2012-3-22
1 个评论
Daniel Shub
2012-3-25
If your question is now answered, then accept your answer and upvote anyone that helped.
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2012-3-20
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2021-8-20
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