> Let 'dd' be a data frame given as:
>
> dd=data.frame(aa=c("a","a","b","a","b","b"),bb=c(1,1,1,2,3,4))
>
> Now I want to create a column 'g' such that if dd$aa=a then dd$g=1 else
> dd$g= -1 .
You need to use ifelse instead of the if ... else construction:
dd$g = ifelse(dd$a=='a', 1, -1)
cu
Philipp
--
Dr. Philipp Pagel Tel. +49-8161-71 2131
Dept. of Genome Oriented Bioinformatics Fax. +49-8161-71 2186
Technical University of Munich
Science Center Weihenstephan
85350 Freising, Germany
and
Institute for Bioinformatics / MIPS Tel. +49-89-3187 3675
GSF - National Research Center Fax. +49-89-3187 3585
for Environment and Health
Ingolstädter Landstrasse 1
85764 Neuherberg, Germany
http://mips.gsf.de/staff/pagel
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