John Hopkins University - Getting and Cleaning Data 

Obtaining Data Motivation

Raw and Processed Data

Components of Tidy Data

Downloading Files

Reading Local Files

Reading Excel Files

Reading XML

Reading JSON

The data.table Package

Reading from MySQL

Reading from HDF

Reading from The Web

Reading From APIs

Reading From Other Sources

Subsetting and Sorting

Summarizing Data

Creating New Variables

Reshaping Data

Managing Data Frames with dplyr - Introduction

Managing Data Frames with dplyr - Basic Tools

Merging Data

Editing Text Variables

Regular Expressions

Regular Expressions

Working with Dates

Data Resources