Adding a simple moving average graph

Now we will create our first simple moving average (SMA) graph. This graph will be created with the   package, and will show two lines. The black line will be the actual price data, and the blue line will be SMA.

Before we begin, and since ggplot2 graphs which make use of dates are better created with actual dates instead of timestamp strings, we add the time column to the ORIGINAL_DATA dataframe with the corresponding dates. This should be placed immediately after having loaded the data:

ORIGINAL_DATA$time <- timestamp_to_time.TimeStamp(ORIGINAL_DATA$timestamp)

Next we show how our sma_graph() function is implemented. As can be seen, it will receive two parameters, the data dataframe and the sma vector coming out of one of the SMA implementations mentioned before. The function is very simple, it creates a graph with time on the x axis and price_usd on the y axis, adds points and lines for such data, and then adds a second blue line with the values from...