R apply function with multiple parameters

Question

I have a function f var1  var2  in R  Suppose we set var2   1 and now I want to apply the function f   to the list L  Basically I want to get a new list L  with the outputs    f L 1  1  f L 2  1      f L n  1     How do I do this with either apply  mapply or lapply

User · Answer

If your function have two vector variables and must compute itself on each value of them (as mentioned by @Ari B. Friedman) you can use mapply as follows:

vars1<-c(1,2,3)
vars2<-c(10,20,30)
mult_one<-function(var1,var2)
{
   var1*var2
}
mapply(mult_one,vars1,vars2)

which gives you:

> mapply(mult_one,vars1,vars2)
[1] 10 40 90

User · Answer

To further generalize  Alexander s example  outer is relevant in cases where a function must compute itself on each pair of vector values   vars1 lt -c 1 2 3  vars2 lt -c 10 20 30  mult one lt -function var1 var2       var1 var2   outer vars1 vars2 mult one    gives    gt  outer vars1  vars2  mult one         1    2    3   1     10   20   30  2     20   40   60  3     30   60   90

User · Answer

Just pass var2 as an extra argument to one of the apply functions   mylist  lt - list a 1 b 2 c 3  myfxn  lt - function var1 var2     var1 var2   var2  lt - 2  sapply mylist myfxn var2 var2    This passes the same var2 to every call of myfxn   If instead you want each call of myfxn to get the 1st 2nd 3rd etc  element of both mylist and var2  then you re in mapply s domain

[r] R apply function with multiple parameters

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