[R] vectorize an expression

Huntsinger, Reid reid_huntsinger at merck.com
Wed Apr 2 21:18:16 CEST 2003

You could calculate the index vector like

ind <- n * (cc - 1) + (1:n)

and then use it to index bb as a vector

aa <- bb[ind]

Reid Huntsinger

-----Original Message-----
From: Simon.Gatehouse at csiro.au [mailto:Simon.Gatehouse at csiro.au] 
Sent: Wednesday, April 02, 2003 2:15 AM
To: r-help at stat.math.ethz.ch
Subject: [R] vectorize an expression

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]]

Any suggestion received with embarrassment and gratitude

Simon Gatehouse                                  
CSIRO Exploration and Mining,
Newbigin Close off Julius Ave
North Ryde, NSW
Mail:      PO Box 136, North Ryde
           NSW 1670, Australia
Phone:     61 (2) 9490 8677
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E-mail:    simon.gatehouse at csiro.au
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