categorical vars in gam

gam.R

library(mgcv)


# From the man page without categorical.
set.seed(2) ## simulate some data... 
dat <- gamSim(1,n=400,dist="normal",scale=2)


b <- gam(y~s(x0)+s(x1)+s(x2)+s(x3),data=dat)
summary(b)

plot(b,pages=1,residuals=TRUE)  ## show partial residuals

preds <- predict(b, newdata = dat)



# Now add categorical
dat2 <- cbind(dat, 
              categ = factor(sample(letters[1:3], nrow(dat), replace = TRUE)),
              categ2 = factor(sample(letters[1:3], nrow(dat), replace = TRUE)))

b2 <- gam(y~s(x0)+s(x1)+s(x2)+s(x3) + categ + categ2, data = dat2)
summary(b2)

plot(b2, pages=1, residuals=TRUE)  ## show partial residuals

preds <- predict(b2, newdata = dat2)