Calendar maps are used to display continuous data over a period of time. Calendar plots have been used to display data on a daily or monthly basis, where each square represents a data point.

In the past, Nathan Yau, in his fatal car crashes, has used calendar heat maps to study the safest time of the year to travel. Using stock prices as input in our calendar map assists us in conducting event study or holiday and weekend effects. We can also apply calendar maps to study airline delays during the days of the month or crime rates during specific times of the year.

In this recipe, we will use the calendar plot to study the daily stock price movement of Facebook over 2013. In order to extract the stock prices from Yahoo Finance, we will use the quantmod package and construct a calendar plot using the googleVis package.