Simulate rolling dice

Simulate and optionally plot rolls of dice.

dice(rolls = 1, ndice = 2, sides = 6, plot.it = FALSE, load = rep(1, sides))
# S3 method for class 'dice'
plot(x, ...)

Arguments

rolls: Scalar, the number of times to roll the dice.
ndice: Scalar, the number of dice to roll each time.
sides: Scalar, the number of sides per die.
plot.it: Logical, Should the results be plotted.
load: Vector of length sides, how the dice should be loaded.
x: Data frame, return value from dice.
...: Additional arguments passed to lattice plotting function.

Details

Simulates the rolling of dice. By default it will roll 2 dice 1 time and the dice will be fair. Internally the sample function is used and the load option is passed to sample. load is not required to sum to 1, but the elements will be divided by the sum of all the values.

Value

A data frame with rolls rows and ndice columns representing the results from rolling the dice.

If only 1 die is rolled, then the return value will be a vector.

If plot.it is TRUE, then the return value will be invisible.

Author

Greg Snow 538280@gmail.com

Note

If the plot function is used or if plot.it is TRUE, then a plot will be created on the current graphics device.

Examples


# 10 rolls of 4 fair dice
dice(10,4, plot.it=TRUE)


# or

plot(dice(10,4))


# or

tmp <- dice(10,4)
plot(tmp)


# a loaded die
table(tmp <- dice(100,1,plot.it=TRUE, load=6:1 ) )

#> Red
#>  1  2  3  4  5  6 
#> 27 28 22 10  8  5 
colMeans(tmp)
#>  Red 
#> 2.59 

# Efron's dice
ed <- list( rep( c(4,0), c(4,2) ),
  rep(3,6), rep( c(6,2), c(2,4) ),
  rep( c(5,1), c(3,3) ) )

tmp <- dice( 10000, ndice=4 )
ed.out <- sapply(1:4, function(i) ed[[i]][ tmp[[i]] ] )

mean(ed.out[,1] > ed.out[,2])
#> [1] 0.664
mean(ed.out[,2] > ed.out[,3])
#> [1] 0.6652
mean(ed.out[,3] > ed.out[,4])
#> [1] 0.6666
mean(ed.out[,4] > ed.out[,1])
#> [1] 0.6742


## redo De Mere's question

demere1 <- dice(10000,4)
demere2 <- dice(10000,24,sides=36)

mean(apply( demere1, 1, function(x) 6 %in% x ))
#> [1] 0.5122

mean(apply( demere2, 1, function(x) 36 %in% x))
#> [1] 0.4959

plot(demere1[1:10,])


## plot all possible combinations of 2 dice

plot.dice( expand.grid(1:6,1:6), layout=c(6,6) )