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Topic: Extracting particular row of a matrix based on specific condition
Replies: 14   Last Post: Jan 3, 2014 10:03 AM

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 Bruno Luong Posts: 9,631 Registered: 7/26/08
Re: Extracting particular row of a matrix based on specific condition
Posted: Jan 1, 2014 4:50 AM

dpb <none@non.net> wrote in message <l9ulhp\$sf7\$1@speranza.aioe.org>...
> On 12/31/2013 2:16 AM, Bruno Luong wrote:
> > B(ismember(A,B(:,1)),2:end)
>
> That returns the rows in B for which the indices are found in A, not B,
> unfortunately, Bruno. It does get the first one correct as they're both
> in position 2, but then it returns fourth row, not first where the last
> element of A is found in first column of B...

You are write, it learns me not to do things too fast.

>
> >> [~,lb]=ismember(A,B(:,1));
> >> B(lb(lb>0),2:end)

> ans =
> 0.1300 0.0010 0.8900
> 0.1200 0.0050 0.1000

> >>
>

Should use the first argument of ismember() rather than recomputing it. Also OP requires the original order, so sort() will fix the order:

[t, iB] = ismember(A,B(:,1));
B(sort(iB(i)),2:end)

% Bruno

Date Subject Author
12/29/13 Pg
12/29/13 Pg
12/29/13 dpb
12/29/13 Pg
12/30/13 dpb
12/31/13 Bruno Luong
12/31/13 dpb
1/1/14 Bruno Luong
1/2/14 dpb
1/2/14 Pg
1/2/14 dpb
1/3/14 dpb
1/2/14 Bruno Luong
1/2/14 dpb
1/3/14 dpb