On 16-Jul-07 14:16:10, Gabor Grothendieck wrote:
> Following up on your comments it seems formula.data.frame just creates
> a formula whose lhs is the first column name and whose rhs is made up
> of the remaining column names. It ignores the "formula" attribute.
>
> In fact, CO2 does have a formula attribute but its not extracted by
> formula.data.frame:
>
>> [EMAIL PROTECTED]
> uptake ~ conc | Plant
>> formula(CO2)
> Plant ~ Type + Treatment + conc + uptake
Indeed! And, following up yet again on my own follow-up comment:
library(combinat)
for(j in (1:4)){
for(i in combn((1:4),j,simplify=FALSE)){
print(formula(CO2[,c(5,i)]))
}
}
uptake ~ Plant
uptake ~ Type
uptake ~ Treatment
uptake ~ conc
uptake ~ Plant + Type
uptake ~ Plant + Treatment
uptake ~ Plant + conc
uptake ~ Type + Treatment
uptake ~ Type + conc
uptake ~ Treatment + conc
uptake ~ Plant + Type + Treatment
uptake ~ Plant + Type + conc
uptake ~ Plant + Treatment + conc
uptake ~ Type + Treatment + conc
uptake ~ Plant + Type + Treatment + conc
opening the door to automated fitting of all possible models
(without interactions)!
Now if only I could find out how to do the interactions as well,
I would never need to think again!
best wishes,
Ted.
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E-Mail: (Ted Harding) <[EMAIL PROTECTED]>
Fax-to-email: +44 (0)870 094 0861
Date: 16-Jul-07 Time: 15:40:36
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