sorry for having bothering you. I found the problem. It was the a stupid error made by me. R could not recognise the variable as it is of course case sensitive for names. So I specified the wrong variable name and R did complain about it with "numeric(0)".
Ulrich
Peter Dalgaard BSA wrote:
Ulrich Leopold <[EMAIL PROTECTED]> writes:
Dear list,
could someone point me to the right command to subtract 2 columns in a data.frame. Might be a bit embarrassing question. But I cannot figure out how to do this simple command in R.
E.g.,
mydata$difference <- mydata$x - mydata$y
-- __________________________________________________
Ulrich Leopold MSc.
Department of Physical Geography Institute for Biodiversity and Ecosystem Dynamics Faculty of Science University of Amsterdam Nieuwe Achtergracht 166 NL-1018WV Amsterdam
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