On Nov 21, 2007, at 11:45 AM, John Chambers wrote: > Simon Urbanek wrote: James, > > On Nov 21, 2007, at 8:22 AM, James Milks wrote: > >> The '=' sign can be used in place of '<-'. That's the only >> shorthand I know for R. >> > > That's not a shorthand. `=` and `<-` are semantically different in R. > Well, not really :-) > > It's true that the "=" operator won't be displayed as "<-", which I > agree was the original point. But both assignment operators map > into the same internal C code, if you di g into the implementation. >
I think we may be talking about different things here. > a=list(a=1,b=2) > ls() [1] "a" > a<-list(a<-1,b<-2) > ls() [1] "a" "b" So `<-` and `=` are *not* semantically equivalent (where `<-` and `=` represent symbols in the parse tree). And I suppose the misunderstanding comes from the interpretation of `=` and `<-`: I meant them as symbols (which is what I would expect since we're talking about writing R code) and you interpreted them as operators (which cold be expected given that I used backticks which was not wise ;)). You are right that `=` and `<-` are equivalent as operators: > `=`(a,list(`=`(a,1),`=`(b,2))) > ls() [1] "a" "b" I hope this makes things even more clear ;). Cheers, Simon > The "=" operator was added in S4 to assuage folks with C/Java/ > awk .... backgrounds who didn't care for the weird assignment > operator. But "real" S and R users still seem to like "<-" better. > > Alexy was asking presumably about shorthands that you press/type in > the R Mac GUI which will result in `<-` being produced and those are > <Alt><-> (this comes from Emacs' "_" shortcut which you type on US > keyboard as <Shift><-> but given that the character _ is often used > these days, we created a variant where you use <Alt> instead of > <Shift>) and <Ctrl><=> (this one is simply a play on the equal sign > and should make sense on other keyboards, too). The last shorthand I > mentioned (<Alt>+<=>) is a direct translation of the ≠ sign (which > you get in other programs when pressing <Alt><=>) into R code. > > Cheers, > Simon > > > _______________________________________________ > R-SIG-Mac mailing list > [email protected] > https://stat.ethz.ch/mailman/listinfo/r-sig-mac > _______________________________________________ R-SIG-Mac mailing list [email protected] https://stat.ethz.ch/mailman/listinfo/r-sig-mac
