# This is the R code stripped from the 5profile.pdf handout.

system.time(Sys.sleep(3))
system.time(readLines("http://imdb.com/top250"))
system.time({n=1000000; x=rnorm(n); y=2*x+3+rnorm(n,0,.1); m=lm(y~x)})
x = runif(50)
system.time(sqrt(x))
n = 1000000
system.time({ for (i in seq_len(n)) { sqrt(x) } })

require("microbenchmark")
a=2
b = microbenchmark(2 + 2, 2 + a, sqrt(x), x ^ .5)
str(b)
head(as.data.frame(b), n=15)
print(b)
tapply(X=b$time, INDEX=b$expr, FUN=summary)
boxplot(b)
require("ggplot2"); autoplot(b) # ggplot2 is a graphics package

n=10000; m=matrix(data=as.numeric(1:(n^2)), nrow=n, ncol=n)
system.time(s <- apply(m, 1, sum))
system.time(rs <- rowSums(m))

baby.sapply = function(X, FUN) {
  n = length(X)
  values.FUN = numeric(n)
  for (i in seq_len(n)) {
    values.FUN[i] = FUN(X[i])
  }
  return(values.FUN)
}
x = rnorm(n=10000)
microbenchmark(baby.sapply(X=x, FUN=abs))
baby.sapply.compiled = compiler::cmpfun(baby.sapply) # Compilation here.
microbenchmark(baby.sapply.compiled(X=x, FUN=abs))

x.file = "x.RData"
if (file.exists(x.file)) {
  print("loading")
  load(file=x.file)
} else {
  x = data.frame(height=1:3, weight=4:6) # ... or read 250 web pages, etc. ...
  save(x, file=x.file)
}