• All interesting things in R are done using functions
  • We recognize them because they use ()
• Several functions of the same subject are grouped in a package
• To use functions from a package we need to load them using library()
• If the package is not in your computer, you need to use install.packages()

Knitr is the system that merges R code and Markdown to produce documents that depend on data

It has many functions. We used two of them:

• kable() is a function to produce nicer tables
  • The mandatory input is a data.frame
  • It is similar to the function pander() from the pander package
• knitr::opts_chunk$set() to set the default options for each chunk

• remember to use library(knitr) before using any function of the package
• remember that the RMarkdown document is independent of the Console
• Save your document on the X: drive (when using lab computers)

We will work on reshape2, melt() and aggregate() tomorrow

The original data is not in an easy format

For this exercise you can get the data from

http://anaraven.github.io/static/earthquakes.txt

• What is the format?
• How can you read it?

The world map can be drawn with the following commands

library(maps)
map('world')

The magnitude \(M\) of an earthquake is related to the released energy \(E\) (in joules) according to the following expression¹: \[\log_{10}(E) = 5.24 +1.44 M,\] which is valid for earthquakes over magnitude 5.

Calculate the energy of each earthquake