"<-" and "=" are not universally interchangable.
args(rm)
function (..., list = character(0L), pos = -1, envir = as.environment(pos),
inherits = FALSE)
The call
rm(list <- ls())
assigns the result of ls() to the variable 'list' and passes that value as an
anonymous argument to rm() (Probably more than you want to know: or it would if
rm() didn't have non-standard evaluation rules -- as it happens, list <- ls()
is recognized as an invalid argument before it is evaluated.)
The call
rm(list=ls())
calls rm() with the 'list' argument having the value of ls()
Here's an example that doesn't confuse things by having non-standard evaluation
rules:
f <- function(a=1, b=2) cat("a=", a, "b=", b, "\n")
b
Error: object 'b' not found
f(b <- 33)
a= 33 b= 2
b
[1] 33
f(b=33)
a= 1 b= 33
-- Tony Plate
Feng Li wrote:
Dear R,
Why rm(list<-ls()) gives an error but rm(list=ls()) not? I remember the
operator ‘<-’ can be used anywhere...
Thanks!
Feng
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