diff -r 9b5165b8a762 -r 0587ef444547 Attic/drumb.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/Attic/drumb.scala	Sat Mar 11 23:22:05 2023 +0000
@@ -0,0 +1,62 @@
+// Advanvced Part 3 about really dumb investing strategy
+//=======================================================
+
+//two test portfolios
+
+val blchip_portfolio = List("GOOG", "AAPL", "MSFT", "IBM", "FB", "YHOO", "AMZN", "BIDU")
+val rstate_portfolio = List("PLD", "PSA", "AMT", "AIV", "AVB", "BXP", "CBG", "CCI", 
+                            "DLR", "EQIX", "EQR", "ESS", "EXR", "FRT", "GGP", "HCP") 
+
+
+// (1) The function below should obtain the first trading price
+// for a stock symbol by using the query
+//
+//    http://ichart.yahoo.com/table.csv?s=<<symbol>>&a=0&b=1&c=<<year>>&d=1&e=1&f=<<year>> 
+// 
+// and extracting the first January Adjusted Close price in a year.
+
+def get_first_price(symbol: String, year: Int): Option[Double] = ...
+
+// Complete the function below that obtains all first prices
+// for the stock symbols from a portfolio for the given
+// range of years
+
+def get_prices(portfolio: List[String], years: Range): List[List[Option[Double]]] = ...
+
+// test case
+//val p = get_prices(List("GOOG", "AAPL"), 2010 to 2012)
+
+
+// (2) The first function below calculates the change factor (delta) between
+// a price in year n and a price in year n+1. The second function calculates
+// all change factors for all prices (from a portfolio).
+
+def get_delta(price_old: Option[Double], price_new: Option[Double]): Option[Double] = ...
+
+def get_deltas(data: List[List[Option[Double]]]):  List[List[Option[Double]]] = ...
+
+// test case using the prices calculated above
+//val d = get_deltas(p)
+
+
+// (3) Write a function that given change factors, a starting balance and a year
+// calculates the yearly yield, i.e. new balanace, according to our dump investment 
+// strategy. Another function calculates given the same data calculates the
+// compound yield up to a given year. Finally a function combines all 
+// calculations by taking a portfolio, a range of years and a start balance
+// as arguments.
+
+def yearly_yield(data: List[List[Option[Double]]], balance: Long, year: Int): Long = ... 
+
+//test case
+//yearly_yield(d, 100, 0)
+
+def compound_yield(data: List[List[Option[Double]]], balance: Long, year: Int): Long = ... 
+
+def investment(portfolio: List[String], years: Range, start_balance: Long): Long = ...
+
+
+//test cases for the two portfolios given above
+//investment(rstate_portfolio, 1978 to 2016, 100)
+//investment(blchip_portfolio, 1978 to 2016, 100)
+