[R] Stata/Rstudio evil attributes

[Koenker, Roger W]

As shown in the reproducible example below, I used the RStudio function haven() to read a Stata .dta file, and then tried to do some fitting with the resulting data.frame.  This produced an error from my fitting function rqss() in the package quantreg.  After a bit of frustrated cursing, I converted the data.frame, D, to a matrix A, and thence back to a data.frame B, and tried again, which worked as expected.  The conversion removed the attributes of D.  My question is:  why were the attributes inhibiting the fitting?

In accordance with the usual R-help etiquette I first tried to contact the maintainer of the haven package, i.e. RStudio, which elicited the response: "since the error is occurring outside RStudio we’re not responsible, so try Stack Overflow".  This is pretty much what I would have expected from the capitalist running dogs they are.  Admittedly, the error is probably due to some unforeseen infelicity in my rqss() coding, but it does seem odd that attributes could have such a drastic  effect.  I would be most grateful for any insight the R commune might offer.

#require(haven) # for reading dta file
#Ddta <- read_dta(“foo.dta")
#D <- with(Ddta, data.frame(y = access_merg, x = meannets_allhh, z = meanhh))
#save(D, file = "D.Rda")
con <- url("http://www.econ.uiuc.edu/~roger/research/data/D.Rda")
load(con)

# If I purge the Stata attributes in D:
A <- as.matrix(D)
B <- as.data.frame(A)

# This works:
with(D,plot(x, y, cex = .5, col = "grey"))
taus <- 1:4/5
require(quantreg)
for(i in 1:length(taus)){
    f <- rqss(y ~ qss(x, constraint = "I", lambda = 1), tau = taus[i], data = B)
    plot(f, add = TRUE, col = i)
}
# However, the same code with data = D, does not.  Why?