CS计算机代考程序代写 Excel # 20/7/2021

# 20/7/2021
# By Elena
# testing barista example

rm(list=ls())

N <- 10^4 set.seed(123) barista <- sample(0:1, size=N, replace=T, prob=c(2/7,5/7)) coffee <- numeric(N) coffee.probs <- array(c(.2,.5,.3,.8,.15,.05),dim=c(3,2)) system.time({ for(i in 1:N){ coffee[i] <- sample(c('Ex','Gd','Ss'), size =1 , replace=T, prob=coffee.probs[,barista[i]+1]) } }) # evaluating conditional inverse probability # Pr(Expert|Excellent) # (remember: mean of a binary vector = proportion of ones in that vector) mean(barista[coffee=='Ex'])