This is a minimal example of using knitr with in HTML pages. I am actually
using markdown here since it is more convenient in GitHub.

First, the input file was named as knitr-minimal.Rmd
(source),
and knitr will automatically determine the output filename to be
knitr-minimal.md (*.Rmd --> *.md).

# set global chunk options: images will be 5x5 inches
opts_chunk$set(fig.width = 5, fig.height = 5)

Now we write some code chunks in this markdown file:

## a simple calculator
(x <- 1 + 1)
## [1] 2
## boring random numbers
set.seed(123)
rnorm(5)
## [1] -0.56048 -0.23018  1.55871  0.07051  0.12929

We can also produce plots:

library(ggplot2)
qplot(hp, mpg, data = mtcars) + geom_smooth()

plot of chunk md-cars-scatter

plot of chunk unnamed-chunk-2

How to use xtable in Markdown!

library(xtable)
print(xtable(head(iris)), type = "html")
Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1 5.10 3.50 1.40 0.20 setosa
2 4.90 3.00 1.40 0.20 setosa
3 4.70 3.20 1.30 0.20 setosa
4 4.60 3.10 1.50 0.20 setosa
5 5.00 3.60 1.40 0.20 setosa
6 5.40 3.90 1.70 0.40 setosa

Inline R code is also supported, e.g. the value of x is 2, and 2 times pi
= 6.2832.

This does not work

read_chunk("~/RStuff/knitrstitch.R")

Equation using \( \frac{1}{n} \sum_{i=i}^{n} x_{i} \)

So no more hesitation on using GitHub and knitr! You just write a minimal
amount of code to get beautiful output on the web.