hadley

df <- setNames(as.data.frame(matrix(nrow = 0, ncol = 2)), c("x", "y"))
# Works
qplot(x, y, data = df)
qplot(x, y, data = df, geom = "smooth")
qplot(x, y, data = df, geom = "density")

# Doesn't work
qplot(x, data = df, geom = "density")

hadley

{
  baseball_df <- data_frame_source(baseball)
  baseball_dt <- data_table_source(baseball)
  baseball_s <- sqlite_source("inst/db/baseball.sqlite3", "baseball")
}

ddply(baseball, "id", summarise, g = mean(g))
#:    user  system elapsed
#:   0.499   0.003   0.503
summarise_by(baseball_s, group("id"), list(g = quote(mean(g))))

hadley

sign1 <- function(x) {
  if (x > 0) {
    1
  } else if (x == 0) {
    0
  } else {
    -1
  }
}

hadley

set_env <- function(envs) {
  stopifnot(is.named(envs))

  old <- Sys.getenv(names(envs), names = TRUE, unset = NA)

  set <- !is.na(envs)
  if (any(set))  do.call("Sys.setenv", as.list(envs[set]))
  if (any(!set)) Sys.unsetenv(names(envs)[!set])

  invisible(old)

hadley

library(Rcpp)
cppFunction('
  NumericVector my_diff(NumericVector x, const int lag) {
    NumericVector y(x.length() - lag);
    int n = x.length();
    for (int i = lag; i < n; i++) {
      y[i - lag] = x[i] - x[i - lag];
    }
    return(y);
  }'

hadley

IntegerVector table1(const CharacterVector x) {
  std::map<char*, int> counts;

  int n = x.length();
  for (int i = 0; i < n; i++) {
    counts[x[i]]++;
  }

  // Loop through each element of map and output into named vector
  IntegerVector out(counts.size());

hadley

cppFunction('
  #include <algorithm>
  IntegerVector findInterval2(NumericVector x, NumericVector breaks) {
    IntegerVector out(x.size());

    NumericVector::iterator it, pos;
    IntegerVector::iterator out_it;

    for(it = x.begin(), out_it = out.begin(); it != x.end(); it++, out_it++) {
      pos = std::upper_bound(breaks.begin(), breaks.end(), *it);

hadley

// [[Rcpp::export]]
LogicalVector duplicated3(IntegerVector x) {
  std::set<int> seen;

  LogicalVector out(x.size());

  IntegerVector::iterator it, end = x.end();
  LogicalVector::iterator out_it;

  for (it = x.begin(), out_it = out.begin(); it != end; ++it, ++out_it) {

hadley

#include <Rcpp.h>
using namespace Rcpp;

double vacc3a(double age, int female, int ily){
  double p = 0.25 + 0.3 * 1 / (1 - exp(0.004 * age)) + 0.1 * ily;
  p = p * (female ? 1.25 : 0.75);
  p = max(p, 0.0); 
  p = min(p, 1.0);
  return p;
}

hadley

#include <Rcpp.h>
using namespace Rcpp;

// [[Rcpp::export]]
double vacc3a(double age, bool female, double ily){
  double p = 0.25 + 0.3 * 1 / (1 - exp(0.04 * age)) + 0.1 * ily;
  p = p * (female ? 1.25 : 0.75);
  p = std::max(p, 0.0); 
  p = std::min(p, 1.0);
  return p;