[Rd] formula(CO2)
(Ted Harding)
ted.harding at nessie.mcc.ac.uk
Mon Jul 16 15:57:56 CEST 2007
On 16-Jul-07 13:28:50, Gabor Grothendieck wrote:
> The formula attribute of the builtin CO2 dataset seems a bit strange:
>
>> formula(CO2)
> Plant ~ Type + Treatment + conc + uptake
>
> What is one supposed to do with that? Certainly its not suitable
> for input to lm and none of the examples in ?CO2 use the above.
I think one is supposed to ignore it! (Or maybe be inspired to
write a mail to the list ... ).
I couldn't find anything that looked like the above formula from
str(CO2). But I did spot that the order of terms in the formula:
Plant, Type, treatment, conc, uptake, is the same as the order
of the "columns" in the dataframe.
So I tried:
D<-data.frame(x=(1:10),y=(1:10))
formula(D)
x ~ y
So, lo and behold, D has a formula!
Or does it? Maybe if you give formula() a dataframe, it simply
constructs one from the "columns".
Best wishes,
Ted.
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Date: 16-Jul-07 Time: 14:57:28
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