Message-ID: <50CD646D.1030808@xtra.co.nz>
Date: 2012-12-16T06:04:29Z
From: Rolf Turner
Subject: Picking out certain elements in an matrix
In-Reply-To: <CAH=5_TUaJwHdL7g96N9GpeTFL2RRroL2CBSbWu_4HjMhBa7-XA@mail.gmail.com>
On 16/12/12 18:38, Tjun Kiat Teo wrote:
> Suppose I have a matrix of data
>
> A
>
> 1 2 3
> 4 5 6
> 7 8 9
>
>
> And I have a vector of indexes 2,1,3
>
> For row 1 of matrix A I want the 2nd element 2
> For row 2 of matrix A I want the 1st element 4
> For row 3 of matrix A I want the 3rd element 9.
>
> Is there a quick way to do it ?
A[cbind(1:3,c(2,1,3))]
cheers,
Rolf Turner