R help es - Jan 2013 - optimización de código en R (Carlos J

Hola Tania

 

Que tal estas soluciones, creo que el tema va por la 4 

 

 

 

sim4 <- function(nreps)  {

nb1 <- 10  # 10 blue marbles in Urn 1

n1 <- 18  # number of marbles in Urn 1 at 1st pick

n2 <- 13  # number of marbles in Urn 2 at 2nd pick

nb2 <- 6 

 

draw1<-ifelse(runif(nreps)<nb1/n1,1,0)

sum(draw2<-ifelse(runif(nreps)<(nb2+draw1)/(n2+draw1),1,0))/nreps

 

}

 

 

sim4b <- function(nreps)  {

                nb1 <- 10  # 10 blue marbles in Urn 1

                n1 <- 18  # number of marbles in Urn 1 at 1st pick

                n2 <- 13  # number of marbles in Urn 2 at 2nd pick

                nb2 <- 6 

                

                draw1<-ifelse(runif(nreps)<nb1/n1,1,0)

                sum(rbinom(nreps,1,(nb2+draw1)/(n2+draw1)))/nreps

                

}

 

 

system.time(sim1(10000))

#    user  system elapsed 

#    0.12    0.00    0.12 

 

 

system.time(sim4(10000))

#    user  system elapsed 

#    0.02    0.00    0.01 

 

 

system.time(sim4b(10000))

#    user  system elapsed 

#    0.02    0.00    0.02 

 

 

 

Paco


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