Delete rows that have the first same value and keep one row in matrix with 2 colums?
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Hi everyone,
I have an array:
x=[0,0 ; 250,1050 ; 250,1051 ; 1173,3050 ; 1173 3150].
I don't know how to delete the rows that has the first value is 250 and just keep one.
The row may be (250,1050) or (250,1051), whatever but just one row.
Could someone please suggest me how to do it?
Many thanks.
2 个评论
Andrew Reibold
2014-11-20
Do you ONLY want the duplicated 250's removed, or ALL of the duplicated values removed (Like the duped 1173 as well)?
Khanh
2014-11-20
采纳的回答
Khanh,
Try something like this. . .
ind250 = x(:,1) == 250;
if numel(ind250)>1
x(ind250(2:end),:) = [];
end
2 个评论
Andrew Reibold
2014-11-20
I think she needs it to work for all duplicates (like 1173 also), not just 250
更多回答（2 个）
C.J. Harris
2014-11-20
Do you mean something like this?
x = [0,0 ; 250,1050 ; 250,1051 ; 1173,3050 ; 1173 3150];
[~,idx] = unique(x(:,1));
out = x(idx,:)
out =
0 0
250 1051
1173 3150
2 个评论
Matt
2014-11-20
Note that the unique will remove all non-unique values, not just the ones with 250 in the first column. Still, if this is the goal, than this is a much better solution than removing elements one by one
Andrew Reibold
2014-11-20
编辑：Andrew Reibold
2014-11-20
This removes any rows where the value in the first column has already been used.
[~,idx] = unique(x(:,1)); %which rows have a unique first value?
x = x(idx,:) %only use those
Output:
x =
0 0
250 1050
1173 3050
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