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Message-ID: <Pine.LNX.4.44.0304020838150.14915-100000@gannet.stats>
Date: 2003-04-02T07:39:05Z
From: Brian Ripley
Subject: vectorize an expression
In-Reply-To: <FFE02AF26875734B82A728403821CB2EFB043A@asp-ri.riverside.csiro.au>

On Wed, 2 Apr 2003 Simon.Gatehouse at csiro.au wrote:

> Dear listers,
> I'm having a bad R day.  I just can't think of the vectorized equivalent of:
> 
> for (ii in 1:n)   aa[ii]  =  bb[ii,cc[ii]]

aa <- bb[cbind(1:n, cc[1:n])]

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595