[R] Problem of intercept?

[varin sacha]

Dear R-experts,

Here below my R code working with quite a few warnings. 
x11 and x12 are dichotomous variable (0=no and 1=yes). I substract 1 to ignore intercept.
I would like not to ignore intercept. How to modify my R code because if I just remove -1 it does not work?


y= c(32,45,65,34,23,43,65,76,87,98,7,867,56,45,65,76,88,34,55,66)
x11=c(0,1,1,0,0,1,1,1,0,0,1,0,0,1,0,0,1,1,0,1)
x12=c(0,1,0,1,0,1,1,0,1,1,0,0,1,1,1,0,0,1,0,0)
 
Dataset=data.frame(y,x11,x12)
 
a=lm(y~x11+x12-1,Dataset)$coef
b=NULL
for(i in c(1:2)) {
  f=formula(paste('y~',names(Dataset)[i],-1))
  b=c(b,lm(f,Dataset)$coef)
}
coef=data.frame(rbind(a,b))
coef$Model=c('Multi','Single')
library(reshape2)
coef.long<-melt(coef,id.vars="Model")
 
library(ggplot2)
ggplot(coef.long,aes(x=variable,y=value,fill=Model))+
  geom_bar(stat="identity",position="dodge")+
  scale_fill_discrete(name="Model",
  labels=c("Multiple", "Simple"))+
  labs(title =paste('La différences des coefficients
  entre la régression multiple et simple'),
  x="Models",y="Coefficient")+
  coord_flip()