Random draws from a multinomial distribution
One random draw from a multinomial distribution or list of multinomial distributions.
rmulti(p)
p |
matrix of dimension |
Returns a vector of length n. Each item represents one draw from the multinomial distribution parameterized by the outcome probabilities in each row of p.
Each row of matrix p must sum to 1 or rmulti will not work properly.
## ## One draw from a three-category multinomial distribution. ## p1 <- c(0.7,0.2,0.1) rmulti(p1) ## ## 10,000 draws from a three-category multinomial distribution. ## n <- 10000 p2 <- matrix(p1,nrow=n,ncol=length(p1),byrow=TRUE) rmdraws <- rmulti(p2) table(rmdraws)/n # should be approximately 0.7, 0.2, 0.1 ## ## 10,000 draws from a mixture of three groups of a ## four-category multinomial distribution. ## group.p <- matrix(c(0.5,0.3,0.2),nrow=n,ncol=3,byrow=TRUE) group <- rmulti(group.p) p3 <- t(matrix(NA,nrow=n,ncol=4)) p3[,group==1] <- c(0.7,0.1,0.1,0.1) p3[,group==2] <- c(0.1,0.7,0.1,0.1) p3[,group==3] <- c(0.1,0.1,0.1,0.7) p3 <- t(p3) rmdraws3 <- rmulti(p3) table(group,rmdraws3) table(group,rmdraws3)/rowSums(table(group,rmdraws3))
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