>>>>> "Ulrich" == Ulrich Leopold <[EMAIL PROTECTED]>
>>>>> on Thu, 04 Sep 2003 14:41:41 +0200 writes:
Ulrich> Dear list, sorry for having bothering you. I found
Ulrich> the problem. It was the a stupid error made by me. R
Ulrich> could not recognise the variable as it is of course
Ulrich> case sensitive for names. So I specified the wrong
Ulrich> variable name and R did complain about it with
Ulrich> "numeric(0)".
Ulrich> Ulrich
Exactly for reasons like these, S language teachers (not all AFAIK) have
recommended to use the slightly more cumbersome
x[,"<varname>"] instead of
x $ <varname>
for things like these:
With the [,".."] form, you immediately get an (intelligible)
error message when you mistype the variable name.
Martin Maechler <[EMAIL PROTECTED]> http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum LEO C16 Leonhardstr. 27
ETH (Federal Inst. Technology) 8092 Zurich SWITZERLAND
phone: x-41-1-632-3408 fax: ...-1228 <><
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
>>
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