[Rd] data.frame within a function (PR#9294) (cont'd)

[Riyan Cheng]

This continues the message "data.frame within a function (PR#9294)" that 
was posted on 2006/10/12. Duncan Murdoch kindly replied. I'm using the 
current version R 2.4.0, but the same issue exists. Just copy and paste 
the following code under R, and compare the output of f1() and f2() and 
the output of f3() and f4(). Does anybody have any idea? Thanks.

###################################################
# R code for demonstration only #
###########################

rmvnorm<- function (n, mean = rep(0, nrow(sigma)), sigma = 
diag(length(mean))){
  if (nrow(sigma) != ncol(sigma)) {
    stop("sigma must be a square matrix")
  }
  if (length(mean) != nrow(sigma)) {
    stop("mean and sigma have non-conforming size")
  }
  ev <- eigen(sigma, sym = TRUE)$values
  if (!all(ev >= -sqrt(.Machine$double.eps) * abs(ev[1])))
    warning("sigma is numerically not positive definite")
  sigsvd <- svd(sigma)
  retval <- t(sigsvd$v %*% (t(sigsvd$u) * sqrt(sigsvd$d)))
  retval <- matrix(rnorm(n * ncol(sigma)), nrow = n) %*% retval
  retval <- sweep(retval, 2, mean, "+")
  retval
}

f<- function(obj){
     update(obj,~ .+x,evaluate=T); cat("also ok\n")
}

#########################
# compare f1() and f2() #
#########################
f1<- function(){
     x<- rnorm(10)
     y<- rmvnorm(10,mean=c(1,2)); colnames(y)<- paste("y",1:2,sep="") 
#c("y1","y2")
     dtf<- data.frame(y,x)
     lm1<- lm(cbind(y1,y2)~1,data=dtf); cat("ok\n")
    
     update(lm1,~ .+x,evaluate=T); cat("also ok\n") # only this line is 
different
}
f2<- function(){
     x<- rnorm(10)
     y<- rmvnorm(10,mean=c(1,2)); colnames(y)<- paste("y",1:2,sep="") 
#c("y1","y2")
     dtf<- data.frame(y,x)
     lm1<- lm(cbind(y1,y2)~1,data=dtf); cat("ok\n")
    
     f(lm1) # only this line is different
}

f1()
f2()

#########################
# compare f3() and f4() #
#########################
f3<- function(){
     x<- rnorm(10)
     y<- rmvnorm(10,mean=c(1,2)); colnames(y)<- paste("y",1:2,sep="") 
#c("y1","y2")
     lm1<- lm(cbind(y1,y2)~1,data=data.frame(y,x)); cat("ok\n")
    
     update(lm1,~ .+x,evaluate=T); cat("also ok\n") # only this line is 
different
}
f4<- function(){
     x<- rnorm(10)
     y<- rmvnorm(10,mean=c(1,2)); colnames(y)<- paste("y",1:2,sep="") 
#c("y1","y2")
     lm1<- lm(cbind(y1,y2)~1,data=data.frame(y,x)); cat("ok\n")
    
     f(lm1) # only this line is different
}

f3()
f4()

#########
# the end #
#########