CS417 Exam 2

You have a collection of stock market summary data in the form of:

{ date, company, start_price, end_price }

where the start_price is the price of the stock at the start of the trading day and the end_price is the price of the stock at the end of that day. For example: { 2014-10-29, AAPL, 106.83, 107.34 }.

You want to find out the average daily gain (or loss) of each company from January 1, 2000 through December 31, 2014. Explain the MapReduce operations needed to accomplish this. Use C/Java style pseudocode. Feel free to use ≤ and ≥ comparisons for dates and assume that functions such as average() are available. Assume that the map function is called once for each parsed record of data and a function called emit() exists in the form emit(key, value). For reduce, assume that a print function exists that prints results. For example, print(name, result).

Answer:

Map function
map(date, company, start_price, end_price) {
	[insert your pseudocode here]

}
Reduce function
reduce(key, list) {
[insert your pseudocode here]

}