CODEWITHSUNDEEP
rrename
Alen
Alen

Reputation: 33

how to use the value of a variable as the name of another variable

In R , how to use the value of a variable as the name of another variable

for example:

SCE<-function(i){
  #x<-paste0("SCE",i)
  x<-c(i,i+1)
  return (x)
}

x<-paste0("SCE",1) 
y<-SCE(1)


paste0("SCE",1)=SCE(1)
cat("SCE",1)=SCE(1)

How can I make the value of variable x (string) as the name of another variable y (unknown data type)? Here, the final result I want to get is a variable named SCE1, its type is numeric, and its value is 1 2

The problem I actually encountered is: I have a repetitive code that I want to use a for loop to complete, but every time I complete it, I want to save the result as a variable so that I can use it later.

SCE<-function(i){
  #x<-paste0("SCE",i)
  x<-c(i,i+1)
  return (x)
}

for (i in 2:9) {
  x<-paste0("SCE",i) 
  y<-SCE(i)
}

Every time the for loop is completed, I hope to get a variable of SCE+number, whose value is the result of the corresponding SCE function

renamne Thank you very much!

Upvotes: 0

Views: 93

Answers (2)

akrun
akrun

Reputation: 887851

The value of

paste0("SCE", 1)
#[1] "SCE1"

We may need the brackets as well

x <-paste0("SCE(", 1, ")")

and then do an eval(parse

eval(parse(text = x))
#[1] 1 2

which is same as executing the function

y <- SCE(1)
y
#[1] 1 2

If the OP wanted to get the values from "SCE1", then extract the function part and the input argument separately

match.fun(sub("\\d+", "", x))(as.numeric(sub("\\D+", "", x)))
#[1] 1 2

If we want to create objects in the global environment (not recommended), an option is list2env, though it is better to store it in a named list

lst1 <- setNames(lapply(1:5, SCE), paste0("SCE", 1:5))
list2env(lst1, .GlobalEnv)

Upvotes: 1

Waldi
Waldi

Reputation: 41260

if I understand your question correctly, assign could be an option :

SCE<-function(i){
  assign(x = paste0("SCE",i), value = c(i,i+1), envir = parent.frame())
}
SCE(1)

SCE1
#> [1] 1 2

Upvotes: 1

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