Matlab Matrix: Eliminating Duplicate Entries
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Hello, all, thanks for reading this post.
I have a problem with a point coordinate matrix I create. I output the matrix correctly, but one of the bugs in the program I inherited is every point after point 1 is duplicated. I looks something like:
0 0 0
0 0 3.0000
0 0 3.0000
0 1.4225 4.8659
0 1.4225 4.8659
0 -1.4269 4.8520
0 -1.4269 4.8520
1.1125 2.3073 6.0264
1.1125 2.3073 6.0264
-1.1160 2.3007 6.0177
-1.1160 2.3007 6.0177
1.1086 -2.3144 6.0039
1.1086 -2.3144 6.0039
-1.1120 -2.3078 5.9953
-1.1120 -2.3078 5.9953
for 8 coordinates (and 7 connections, as this is a binary tree).
Is there a way to output a new point coordinate matrix where I have 8 rows, and no duplicate points?
Thanks
Edit: unique(A,'rows') will work in my case (because the point coordinates are exactly the same), but when I use it it outputs the coordinates in alpha-numeric order. Is there a way to output the coordinates in their original order, minus the duplicates?
采纳的回答
Fangjun Jiang
2011-11-17
0 个投票
unique(A,'rows')
6 个评论
Walter Roberson
2011-11-17
Note: if the above does not work, then the duplicates might not be *exact* duplicates -- e.g., the difference between them might be on the order of 1E-15 . If that is the case, you might need a different strategy.
Brian
2011-11-17
Fangjun Jiang
2011-11-17
Yes. the output of unique() is sorted. You can do this to get the original order.
a=[9 8 9 7 6 7 5 4 8];
[b,ind]=unique(a,'first');
b=a(sort(ind));
Brian
2011-11-17
Walter Roberson
2011-11-17
Using the indexing I suggested in my answer would deal with these issues much more readily...
Fangjun Jiang
2011-11-17
It's a matter of selecting all the columns.
b=a(sort(ind),:)
更多回答（1 个）
Walter Roberson
2011-11-17
A(1:2:end,:)
This does not have the problem with comparing nearly equal quantities, but it does assume that the second row of each pair is acceptable
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