This is a subset problem, not a problem with plot or lm. You need to
read eg help("[.data.frame")
Here are two working examples:
# df already means something!
mydf <- data.frame(out=1:4*3,pred1=1:4,pred2=1:4*2)
regression <- function(tble,a,b)
{
plot.new()
plot(tble[,a]~tble[,b])
lmm=lm(tble[,a]~tble[,b])
abline(lmm)
anova(lmm)
}
regression(mydf, 1, 3)
regression <- function(tble,a,b)
{
plot.new()
plot(tble[[a]]~tble[[b]])
lmm=lm(tble[[a]]~tble[[b]])
abline(lmm)
anova(lmm)
}
regression(mydf, 1, 3)
Sarah
On 6/4/07, Stan Hopkins <[EMAIL PROTECTED]> wrote:
> I'm new to R and am trying to extract the factors of a dataframe using
> numeric indices (e.g. df[1]) that are input to a function definition instead
> of the other types of references (e.g. df$out). df[1] is a list(?) whose
> class is "dataframe". These indexed lists can be printed successfuly but are
> not agreeable to the plot() and lm() functions shown below as are their
> df$out references. Reading the documentation for plot and lm hasn't helped
> yet. Thanks in advance - Stan.
>
> > df=data.frame(out=1:4*3,pred1=1:4,pred2=1:4*2)
> > regression=function(tble,a,b)
> + {
> + plot.new()
> + plot(tble[a]~tble[b])
> + lmm=lm(tble[a]~tble[b])
> + abline(lmm)
> + anova(lmm)
> + }
> > df[1]
> out
> 1 3
> 2 6
> 3 9
> 4 12
> > df
> out pred1 pred2
> 1 3 1 2
> 2 6 2 4
> 3 9 3 6
> 4 12 4 8
> > regression(df,1,3)
> Error in model.frame(formula, rownames, variables, varnames, extras,
> extranames, :
> invalid type (list) for variable 'tble[a]'
> >
>
>
--
Sarah Goslee
http://www.functionaldiversity.org
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