I have a function that takes a vector and returns some output.
my.function <- function(x){
if (1 %in% x) {
first.data <- data.frame(a = c(1, 2), b = c("a", "b"))
return(first.data)
}
if (2 %in% x){
second.data <- data.frame(a = c("I", "II"), b = c("a", "b"))
return(second.data)
}}
my.function(x = c(1, 2))
a b
1 a
2 b
Why does my function not return both first.data as well as second.data?
You can simple call the function using lapply as follow:
lapply(1:2,my.function)
Output:
[[1]]
a b
1 1 a
2 2 b
[[2]]
a b
1 I a
2 II b
If you would like to follow your approach then:
my.function <- function(x){
for(i in 1:length(x)){ # This will call for each element in x
if (1 %in% x) {
first.data <- data.frame(a = c(1, 2), b = c("a", "b"))
data = (first.data) # Store intermediate result to data
}
if (2 %in% x){
second.data <- data.frame(a = c("I", "II"), b = c("a", "b"))
data=rbind(data,second.data) # Row wise bind the result
}
return(data) # Return the data
}
}
my.function(x = c(1, 2))
Output:
a b
1 1 a
2 2 b
3 I a
4 II b
Whenever return statement executed, it won't execute next steps in a function. If you want to return both the outputs, use return to send the final output.
my.function <- function(x){
first.data<-data.frame()
second.data<-data.frame()
if (1 %in% x) {
first.data <- data.frame(a = c(1, 2), b = c("a", "b"))
}
if (2 %in% x){
second.data <- data.frame(a = c("I", "II"), b = c("a", "b"))
}
return(list(first.data,second.data))
}
return(first.data) and return(second.data) in the end.This should work:
my.function <- function(x){
first.data <- data.frame()
second.data <- data.frame()
if (1 %in% x) {
first.data <- data.frame(a = c(1, 2), b = c("a", "b"))
}
if (2 %in% x){
second.data <- data.frame(a = c("I", "II"), b = c("a", "b"))
}
list(first.data, second.data) # last element not declared is returned.
}
No need for return.
Keep in mind that if the if-statement is evaluated as FALSE, it will throw an error because the function won't find first.data or second.data.
lapply(c(1, 2), my.function)? OrVectorize(my.function, SIMPLIFY = F)your function.returncommand in a function and not multiplereturn?