function that uses a variable name as the parameter
On 12/11/2008 7:59 AM, David Croll wrote:
Hello dear R people!
Several times it occurred to me that a function that uses a variable name as a parameter would be helpful, but I did not find out how to write such a function. I have experience in several programming language, but I did not come across a helpful trick...
What I want to have is...
a <- 12 # starting value
add <- function(variable,increment) {
variable <- variable + increment
}
# by typing a and 25 for example, you specify that 25 will be added to the variable a...
add(a,25)
# the new a equals 12 + 25 = 37
Thanks for all the help ? I'll try to give my advice when I get across a problem I can solve!
That's not a good idea: it looks as though you're trying to fake "call by reference" in a call by value language. R is flexible enough to do it (use substitute() to change the arg into a string, get() to get the old value, assign() to put it back), but the behaviour will be really weird, and you'll probably run into problems later. R is not C. Duncan Murdoch