You can use the get() function in R to retrieve named objects.
Here are the three most common get() functions in R:
1. get() – Retrieve one object
get("my_object")
2. get0() – Retrieve one object, using custom error message if not found
get0("my_object", ifnotfound="does not exist")
3. mget() – Retrieve multiple objects
mget(c("my_object1", "my_object2", "my_object3"))
The following examples show how to use each function in practice.
Example 1: Use get() to Retrieve One Object
The following code shows how to use the get() function to retrieve one name object:
#define vector of values
data1 <- c(4, 5, 5, 6, 13, 18, 19, 15, 12)
#get vector of values
get("data1")
[1] 4 5 5 6 13 18 19 15 12
If the named object does not exist, this function returns an error:
#define vector of values
data1 <- c(4, 5, 5, 6, 13, 18, 19, 15, 12)
#attempt to get vector of values
get("data0")
Error in get("data0") : object 'data0' not found
Example 2: Use get0() to Retrieve Object, Using Custom Error Message
We can also use the get0() function to retrieve a named object in R and use a custom error message if the object is not found:
#define vector of values
data1 <- c(4, 5, 5, 6, 13, 18, 19, 15, 12)
#attempt to get vector of values
get0("data0", ifnotfound="does not exist")
[1] "does not exist"
Since the named object “data0” does not exist, the get0() function returns the custom error message that we created.
Example 3: Use mget() to Retrieve Multiple Objects
We can use the mget() function to retrieve multiple named objects in R:
#define three vectors
data1 <- c(4, 5, 5, 6, 13, 18, 19, 15, 12)
data2 <- c("A", "B", "C", "D")
data3 <- c(10, 20, 25, 30, 35)
#get all three vectors
mget(c("data1", "data2", "data3"))
$data1
[1] 4 5 5 6 13 18 19 15 12
$data2
[1] "A" "B" "C" "D"
$data3
[1] 10 20 25 30 35
Note that if we just tried to use the get() function, only the first named object would be returned:
#define three vectors
data1 <- c(4, 5, 5, 6, 13, 18, 19, 15, 12)
data2 <- c("A", "B", "C", "D")
data3 <- c(10, 20, 25, 30, 35)
#attempt to get all three vectors
mget(c("data1", "data2", "data3"))
[1] 4 5 5 6 13 18 19 15 12
Additional Resources
The following tutorials explain how to use other common functions in R:
How to Use the c() Function in R
How to Use the sprintf() Function in R
How to Use the replace() Function in R