## session 6 # Some profiler examples # - use Rprof(filename), Rprof(NULL) to profile them # With more careful coding, we can make the calculation much quicker system.time({ my.sims <- replicate(10000, { mydiff <- rnorm(100, 2, 7) t.test(mydiff)$p.value }) }) system.time({ my.sims <- replicate(10000, { mydiff <- rnorm(100, 2, 7) t <- mean(mydiff)/sd(mydiff)*sqrt(100) 2*pt(-abs(t), df=99) }) }) crit.t <- qt(0.975, df=99) system.time({ my.sims <- replicate(10000, { mydiff <- rnorm(100, 2, 7) t <- mean(mydiff)/sd(mydiff)*sqrt(100) abs(t)>crit.t }) }) system.time({ mydiffs<-matrix(rnorm(100*10000,2,7),nrow=100) m<-colMeans(mydiffs) s<-sqrt(colMeans(mydiffs*mydiffs)-m*m) m*sqrt(100)/s > crit.t }) crit2<-crit.t^2/100 system.time({ mydiffs<-matrix(rnorm(100*10000,2,7),nrow=100) m2<-colMeans(mydiffs)^2 s2<-colMeans(mydiffs*mydiffs)-m2 m2/s2 > crit2 })