I have a function that looks like
my_function <- function(object)
{
# code goes here
}
I'd like the function (among other things) to print the name of the argument (as passed to the function). So if my function call is:
xxx <- my_function(my_object)
then I'd like to know how to get the function to print out the string "my_object".
Can anyone help please?
A more R-ish solution would be to use substitute (get substitute for obj) in combination with deparse (cast symbol to string):
my_function <- function(obj) {deparse(substitute(obj))}
General R metaprogramming rule: prefer substitute!
my_function(my_object)
## [1] "my_object"
I would suggest next approach which is closer to what you want. For sure you could modify it to obtain other outputs:
#Function
my_function <- function(x)
{
as.character(eval(parse(text=enquo(x)))[2])
}
#Apply
my_function(x = my_object)
Output:
[1] "my_object"
An improvement thanks to @MrFlick is next:
#Function
my_function <- function(x)
{
rlang::as_label(rlang::enquo(x))
}
#Apply
my_function(x = my_object)
Which produces same output with a more elegant style in the function:
[1] "my_object"
rlang::enquo, it would make more sense to use rlang::as_label(enquo(x)) to get the name out. Otherwise the deparse/substitute is more idiomatic in base R.
To display the entire call use match.call like this:
f <- function(x) { print(match.call()); x }
f(pi)
## f(x = pi)
## [1] 3.141593
IF it is desired to display the call just for debugging without modifying the function itself then use trace:
g <- function(x) x # test function
trace(g)
g(pi)
## trace: g(pi)
## [1] 3.141593
myFunction <- function(x = paste("what you want to pass")){
print(x);
}#end function
my_object?