Creating a function in R with an argument whose inputs begin with a number -

i apologize if has been answered somewhere can't find question similar anywhere.

i trying create function 1 of input arguments (but isn't necessarily) string begins number. when try run function, r confused.

for example:

foo(df, 10, 5fum) 

gives me error:

error: unexpected symbol in "do_cv_class(data,10,5fum"

in function plan on taking "5fum" , parsing 2 arguments "5" , "fum". don't want create 4th argument separate 5 , fum.

any ideas? on great.

as comments above suggest, need pass "5fum" string. without rewriting r's parser, it's impossible think of way foo(df, 10, 5fum) legal input. presumably you're thinking this:

foo <- function(df, num1, str1) {    str1_num <- as.numeric(gsub("([0-9]+)([[:alpha:]]+)","\\1",str1))    str1_alpha <- gsub("([0-9]+)([[:alpha:]]+)","\\2",str1)    print(str1_num)    print(str1_alpha) }  foo(df, 10, "5fum") ## [1] 5 ## [1] "fum" 

(i thought passing argument ~5fum might work, ~ prevents subsequent symbols being evaluated immediately, doesn't: symbol 5fum still needs parsed.)