hadley

# server.R

library("shiny")

shinyServer(
  function(input, output){

    output$displayCounter <- renderText({
        c("value of counter:", updateCounter())
    })

hadley

vectorised_r <- function(x, y) {
  exp(-abs(x - y))
}

devectorised_r <- function(x, y) {
  r <- rep(NA, length(x))
  for(i in seq_along(x)) {
    r[i] <- exp(-abs(x[i] - y[i]))
  }
  r

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# lazy data frame
#
# like idata.frame, but exploits lazy evaluation + macro code generation
# instead of active bindings
library(vadr)

lazy.frame <- function(df, enclos=parent.frame(), ...) UseMethod("lazy.frame")

lazy.frame.lazy.frame <- function(df, ...) df

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# User facing function
#
# to_math(x[1] + 1^{2 + 4} + 5 + sqrt(y) / 5 %/% 10)
# to_math(paste(x^2, y - 1, z_i))
# to_math(hat(tilde(ring(x))))
# to_math(pi*r^2)
# to_math(unknown_call(x, floor(sqrt(z))))
# to_math(u1(x) + u2(x))
to_math <- function(x) {
  x <- substitute(x)

hadley

Load Data With Hmisc

Often times when working with data in R, you find yourself needing to summarise a data.frame by a column, a SELECT SUM(..) or SELECT COUNT(..) in MySQL if you will.

For instance, you may have a lot of page-visits to analyse and you aren't quite certain how to summarise some of that data using R.

Let's consider the following (trivial) dataset: