[R] loop is going to take 26 hours - needs to be quicker!

David Barron mothsailor at googlemail.com
Thu Dec 14 14:33:42 CET 2006


What about

gpcc.array <- array(gpcc.data2[,5], dim=c(144,72,46))

On 14/12/06, Rainer M Krug <RKrug at sun.ac.za> wrote:
> Jenny Barnes wrote:
> > Dear R-help,
> >
> > I have a loop, which is set to take about 26 hours to run at the rate it's going
> > - this is ridiculous and I really need your help to find a more efficient way of
> > loading up my array gpcc.array:
> >
> > #My data is stored in a table format with all the data in one long column
> > #running though every longitute, for every latitude, for every year. The
> > #original data is sotred as gpcc.data2 where dim(gpcc.data2) = [476928,5] where
> > #the 5th column is the data:
> >
> > #make the array in the format I need [longitude,latitude,years]
> >
> > gpcc.array <- array(NA, c(144,72,46))
> >
> > n=0
> > for(k in 1:46){
> > for(j in 1:72){
> > for(i in 1:144){
> > n <- n+1
> > gpcc.array[i,j,k] <- gpcc.data2[n,5]
> > print(j)
> > }
> > }
> > }
>
> I don't know if it is faster - but adding three columns to qpcc.data,
> one for longitude, one for lattitude and one for year (using rep() as
> they are in sequence) and the using reshape() might be faster?
>
>
> >
> > So it runs through all the longs for every lat for every year - which is the
> > order the data is running down the column in gpcc.data2 so n increses by 1 each
> > time and each data point is pulled off....
> >
> > It needs to be a lot quicker, I'd appreciate any ideas!
> >
> > Many thanks for taking time to read this,
> >
> > Jenny Barnes
> >
> > ~~~~~~~~~~~~~~~~~~
> > Jennifer Barnes
> > PhD student - long range drought prediction
> > Climate Extremes
> > Department of Space and Climate Physics
> > University College London
> > Holmbury St Mary, Dorking
> > Surrey
> > RH5 6NT
> > 01483 204149
> > 07916 139187
> > Web: http://climate.mssl.ucl.ac.uk
> >
> > ______________________________________________
> > R-help at stat.math.ethz.ch mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
>
>
> --
> Rainer M. Krug, Dipl. Phys. (Germany), MSc Conservation
> Biology (UCT)
>
> Department of Conservation Ecology and Entomology
> University of Stellenbosch
> Matieland 7602
> South Africa
>
> Tel:            +27 - (0)72 808 2975 (w)
> Fax:            +27 - (0)86 516 2782
> Fax:            +27 - (0)21 808 3304 (w)
> Cell:           +27 - (0)83 9479 042
>
> email:  RKrug at sun.ac.za
>         Rainer at krugs.de
>
> ______________________________________________
> R-help at stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


-- 
=================================
David Barron
Said Business School
University of Oxford
Park End Street
Oxford OX1 1HP



More information about the R-help mailing list