Changing values of a dice roll - r

Question

So let's say I roll 5 dice.
The code to simulate the rolls would be
Rolls<-sample(1:6, 5, replace=TRUE)
and that's if I want to store my rolls under the object Rolls.
Now let's say for some reason I don't want there to be more than 2 sixes. That means if I roll, for example, 6 3 5 6 6 1 would I be able to re-roll one of the 6 values into a new value so that there are only 2 values of 6 and 4 values that are not 6?
Any support would be appreciated.
Thanks in advance

Answer 1

A solution without loops could be:
condition = which(Rolls==6)
if(length(condition)>=3){
Rolls[condition[3:length(condition)]] = sample(1:5, length(condition)-2, replace=TRUE)
}
condition states the places in Rolls with 6's, if there's more than 2, you select the third one onward Rolls[condition[3:length(condition)]] and re-sample them.
And the second question could be something like:
remove = 3
Rolls = Rolls[-which(Rolls==remove)[1]]
You can easily put those into functions if you like
Edit 1
To make the second answer a bit more interactive, you can build a function for it:
remove.roll = function(remove, rolls){
rolls = rolls[-which(rolls==remove)[1]]}
And then the user can call the function with whatever remove he likes. You can also make a program that takes information from the prompt:
remove = readline(prompt="Enter number to remove: ")
print(Rolls = Rolls[-which(Rolls==remove)[1]])

Answer 2

if i understood it correctly, that should work:
n <- 10
(Rolls<-sample(1:6, n, replace=TRUE))
#> [1] 6 2 4 1 1 6 5 2 1 6
(Nr_of_six <- sum(6 == Rolls))
#> [1] 3
while (Nr_of_six > 1) {
extra_roll <- sample(1:6, 1, replace=TRUE)
second_six <- which(Rolls==6)[2]
Rolls[second_six] <- extra_roll
print(Rolls)
Nr_of_six <- sum(6 == Rolls)
}
#> [1] 6 2 4 1 1 4 5 2 1 6
#> [1] 6 2 4 1 1 4 5 2 1 3
print(Rolls)
#> [1] 6 2 4 1 1 4 5 2 1 3
Created on 2021-03-21 by the reprex package (v1.0.0)

Answer 3

We can make this a fun demonstration of a use case for scan(). You can input the position of the values that you want to replace. Note that you need to hand scan() each position value piece by piece and hit enter after every one, in the end you can end the input by handing over an empty string "" and pressing enter.
Code
dice.roll <- function(){
# Initial toss
Rolls <- sample(seq(1, 6), 5, replace=TRUE)
# Communicate
cat("The outcome of the dice roll was:", "\n\n", Rolls, "\n\n",
"would you like to reroll any of those values ?", "\n",
"If yes enter the positions of the values you would \n like to replace, else just input an empty string.")
# Take input
tmp1 <- scan(what = "")
# Replace
Rolls[as.numeric(tmp1)] <- sample(seq(1, 6), length(tmp1), replace=TRUE)
# Return
cat("You succesfully replaced", length(tmp1), "elements. Your rolls now look as follows: \n\n",
Rolls)
}
dice.roll()
# The outcome of the dice Roll was:
#
# 6 4 6 3 4
#
# would you like to reroll any of those values ?
# If yes enter the positions of the values you would
# like to replace, else just input an empty string.
# 1: 1
# 2: 3
# 3: ""
# Read 2 items
# You succesfully replaced 2 elements. Your set now looks as follows
#
# 2 4 2 3 4
Please note that this function is just a quick write-up to properly implement this you should use a while statement or recursion to repeat the replacement as often as you'd like. Additionally, before actually using this one would have to insert if statements that handle inputs that are too long and other user behavior that could cause an error.

Answer 4

Here is my version of this function that uses recursion to roll extra values so that we only have no more than 2 6s. Pay attention that I put rolls vector outside of the function so in order to replace third, fourth or ... 6 from inside the function we use complex assignment operator <<-.
I personally chose to modify the first 6 value in a run of 3 6s or more.
rolls <- sample(1:6, 6, replace = TRUE)
n_six <- function() {
n <- length(rolls[rolls == 6])
if(n <= 2) {
return(rolls)
} else {
extra <- sample(1:6, 1, replace = TRUE)
rolls[which(rolls == 6)][1] <<- extra
}
n_six()
}
# Imagine our rolls would be a vector with 3 six values like this
rolls <- c(1, 2, 6, 5, 6, 6)
> n_six()
[1] 1 2 3 5 6 6 # First 6 was replaced
# Or our rolls contains 4 six values
rolls <- c(1, 6, 6, 5, 6, 6)
> n_six()
[1] 1 4 1 5 6 6 # First 2 6s have been replaced
And so on ...