# Secret Santa Picker 2 using R

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Last year I made a blog post about a Secret Santa picker HERE, but to use it required quite a bit of messing around with the code. So this year I decided to improve the whole thing by making it a function rather than a script. The function take two inputs, a list of names and a number of names. The code for the function is listed first followed by the code for the script used to call the function.

Here’s the function. Nothing needs to be changed in this code for it to run properly.

# make a function secret_santa <-function(npeople, names){ # this 'flag' is used to determine if the # function stays in or out of the while function flag = "bad" # first list of names namelist1 = matrix(names, ncol = 1, nrow = npeople) fam = matrix(ncol = 1, nrow = npeople, NA) while (flag == "bad"){ # names to choose from namelist2 = matrix(ncol = 1, nrow = npeople, NA) for (i in 1:npeople){ #pick the first name if (i==1){ xx2 = sample(names, (npeople-i+1), replace=FALSE) } else xx2 = sample(xx2, (npeople-i+1), replace=FALSE) if (i == npeople & xx2[1]==namelist1[i,1]){ flag = "bad" }else if(xx2[1]!= namelist1[i,1]){ namelist2[i,1] = xx2[1] flag = "good" } else{ namelist2[i,1] = xx2[2] flag = "good" } #set up the new matrix with one less name used = which(xx2==namelist2[i]) xx2[used] = "zzzzz" xx2 = sort(xx2)[1:(npeople-i)] } #flag #add "has" to the matrix has = matrix(ncol=1, nrow = npeople, "has") #build the final matrices final = cbind(namelist1, has, namelist2) #the final results #final } final }

Save this function as “secret-santa-function.R” and we’ll call it from our script. Okay, now let’s make our script.

# call the function from the script source("secret-santa-function.R") ### Function input ### make a list of names names = c("James","Nick","Emily","Natasha","Bob", "Teddy") n = length(names) #call the function output <-secret_santa(n, names) output

The list of names is the only input needed. In the case above it’s ‘names = c(“James”,”Nick”,”Emily”,”Natasha”,”Bob”, “Teddy”)’. The other variable the function needs is the number of names, which is read automatically from the **length** function. That’s it, you’re done. Call the function from the script and you’ve got your names.

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