I am having trouble with variable scoping inside/outside functions.  I
want to use get() to grab a named and quoted variable as an input to a
function, however the function can't find the variable when it is entered
into the function call, only when it is named in the main environment.

I obviously am not so clear on variable scoping, and ?get really doesn't
clear up my confusion.

I am sure that there are better, more appropriate ways to write a
function...

Please enlighten me,
Pat

# Example code

dat <- expand.grid(a = factor(c("a", "b")), b=1:10)

# Function that requires get()
ex <- function(data, response){
 library(plyr)
 output <- ddply(data,
.(a),
summarize,
 res = sum(get(response))
)
return(output)
}


out <- ex(data = dat, response = "b")
# Error in get(response) : object 'response' not found

# However if I name reponse outside of the function, it is found by the
function
response = "b"
out <- ex(data = dat, response = "b")
out
#> out
#  a res
#1 a  55
#2 b  55


-- 
Patrick Schmitz
Graduate Student
Plant Biology
1206 West Gregory Drive
RM 1500

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