> library('plyr')
> library('dplyr')
> smp <- sample(99,1000,replace=TRUE)
> split(smp, cut(smp, c(-Inf, c(1,40,60), Inf)))
> dfm <- data.frame(line=smp) %>% tbl_df %>%
mutate(.,d1=ifelse(line>=0&line<40,1,0),
d2=ifelse(line>=40&line<60,1,0),
d3=ifelse(line>=60&line<=99,1,0))
lm(line~d1+d2+d3,data=dfm)
