How can I strip duplicates?
Show older comments

I wish to remove all duplicate rows based off of the first column. That is, I want to just strip the excess away. I am struggling to understand how to implement "unique" here. Thanks in advance
5 Comments
dpb
on 8 Apr 2021
Looks like you probably just want the 'rows' optional parameter...
res=unique(data,'rows'); % keep original, too, or
data=unique(data,'rows'); % throw the original duplicates away
Cris LaPierre
on 8 Apr 2021
Perhaps something got lost as you transferred your answer here, but it looks like both lines of code will produce the same output.
dpb
on 8 Apr 2021
Yes, but as the comments note the second overwrites the data array whereas the first creates a new result variable, keeping the original data as well in case there is some other reason to have it, too, going forward.
Cris LaPierre
on 9 Apr 2021
Ah, got it. Thanks.
per isakson
on 13 Oct 2021
Edited: per isakson
on 13 Oct 2021
Answers (1)
Fangjun Jiang
on 9 Apr 2021
If you want
- remove duplicates only based on values in the first column
- Do not want the returned values be sorted
then you need to do this
in=[[5;5;5;4;4;4;3;3;3;1],(1:10)'];
[~, index]=unique(in(:,1),'stable');
out=in(index,:)
Categories
Find more on Shifting and Sorting Matrices in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!