Hi,
I have a problem with fitting a model:
I made a dataframe with this data:
a <- 1:3
b <- 1:3
c <- c(3, 2, 3, 2, 1, 2, 3, 2, 3)
df <- expand.grid(a,b)
df$result <- c
names(df) <- c("A","B", "result")
Although I can make a graph of the data:
require(lattice)
wireframe(result~A*B, data=df)
I can't get a model to fit this 3D data.
I have tried the lm function, but its easy to see that this a non lineair data
set. The use of poly also isn't a solution.
I tried to use nls, but there seems to be an error?
mod <- nls(result~A:B, df, start = list (A=0, B=0))
Error in qr.qty(QR, resid) : 'qr' and 'y' must have the same number of rows
Is there a way to fit this data?
Thanks for your time by reading this, hopefully I will get an answer.
Bart Joosen
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