plotConf for lmer models

[bozenne]

Hi Klaus,

Melanie would like to use the plotConf function for mixed models (e.g. lmer object).
But she gets the following error:
"Error in if (fixed.only) { : argument is of length zero"

example:

library(lme4)
library(lava)
n <- 100
x0 <- rnorm(n)
x1 <- seq(-3,3, length.out=n)
x2 <- factor(rep(c(1,2),each=n/2), labels=c("A","B"))
y <- 5 + 2*x0 + 0.5*x1 + -1*(x2=="B")*x1 + 0.5*(x2=="B") + rnorm(n, sd=0.25)
dd <- data.frame(y=y, x1=x1, x2=x2)
dd$Id <- rbinom(n, size = 3, prob = 0.3)
lmer0 <- lmer(y ~ x0 + x1*x2 + (1|Id), dd)
plotConf(lmer0, var1="x1", `var2="x2")

I think this is because lme4:::model.frame.merMod has an additional argument fixed.only compare to the standard stats:::model.frame.lm
I have tried to fixed, as well as another error due to the fact that when extracting the covariance matrix in lmer we get an object and not a matrix (so I have applied as.matrix to it).
In the following file you will find the change that I suggest:
plotConf.txt
(it should be an .R file but I could not load it so I converted it to a .txt file)

Thanks

[kkholst]

Thanks. Merged into the develop branch.