[R] can I do this with read.table??

[Douglas Grove]

Hi,

I'm trying to figure out if there's an automated way to get
read.table to read in my data and *not* convert the character
columns into anything, just leave them alone.  What I'm referring
to as 'character columns' are columns in the data that are quoted.
For columns of alphabetic strings (that aren't TRUE or FALSE) I can
suppress conversion to factor with as.is=TRUE, but what I'd like to
stop is the conversion of quoted numbers of the form "01","02",..., 
into numeric form.
 
By an 'automated way', I mean one that does not involve me having
to know which columns in the data are the ones I want kept as
they are.

This doesn't seem like an unreasonable thing to want to do.
After all, say I've got the data.frame:

  A <- data.frame(a=1:3, b=I(c("01","02","03")))

I can export this to a text file with the simple command

  write.table(A, "A.txt", sep="\t", row.names=FALSE, quote=TRUE)

but I cannot find an equally simple mechanism for reading this
data back in from A.txt that allows me to reconstruct my
data.frame 'A'.  Is this an unreasonable thing to expect?

Thanks,
Doug