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Topic: Conditional Maximum
Replies: 2   Last Post: Nov 24, 2012 3:54 PM

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Roger Stafford

Posts: 5,886
Registered: 12/7/04
Re: Conditional Maximum
Posted: Nov 24, 2012 3:54 PM
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"Rahat" wrote in message <k8r2ca$1ie$1@newscl01ah.mathworks.com>...
> I have 3 columns in my database:
>
> ID Year Tenure
> 12 1992 1
> 12 1993 2
> 12 1994 3
> 12 1995 4
> 225 2001 1
> 225 2002 2
> 225 2003 3
> 225 2004 4
> 225 2005 5
> 225 2006 6
> 3045 2009 1
> 3045 2010 2
> 3045 2011 3
>
> I want to keep IDs with a tenure >=5 years. For that matter I want to create a 4th column containing "Maximum Tenure" against each id such that:
>
> ID Year Tenure MaxTenure
> 12 1992 1 4
> 12 1993 2 4
> 12 1994 3 4
> 12 1995 4 4
> 225 2001 1 6
> 225 2002 2 6
> 225 2003 3 6
> 225 2004 4 6
> 225 2005 5 6
> 225 2006 6 6
> 3045 2009 1 3
> 3045 2010 2 3
> 3045 2011 3 3
>
> How can I do it? Please help.

- - - - - - - - - -
Let A be the array of your database.

A = sortrows(A,[1,3]); % <-- This is in case A is not sorted as in your example
[~,m,n] = unique(A(:,1),'last');
A2 = [A,A(m(n),3)]; % <-- This is the new database

Your request "I want to keep IDs with a tenure >=5 years" seems totally incompatible with your second request. The above is only for the second request.

Roger Stafford



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