# HG changeset patch
# User Christian Urban <urbanc@in.tum.de>
# Date 1478736914 0
# Node ID a7afc2540a8866aae78db6a33b66975cc4fbe447
# Parent  6253f46814513e1cf48a9fb503ca38e510b59248
updated

diff -r 6253f4681451 -r a7afc2540a88 cws/cw01.pdf
Binary file cws/cw01.pdf has changed
diff -r 6253f4681451 -r a7afc2540a88 cws/cw01.tex
--- a/cws/cw01.tex	Wed Nov 09 15:07:23 2016 +0000
+++ b/cws/cw01.tex	Thu Nov 10 00:15:14 2016 +0000
@@ -80,7 +80,7 @@
 \item[(2)] Write a second function that takes an upper bound as
   argument and calculates the steps for all numbers in the range from
   1 up to this bound. It returns the maximum number of steps and the
-  corresponding number that needs that many steps.  More precisely
+  corresponding number that needs that many steps.  More precisely,
   it returns a pair where the first
   component is the number of steps and the second is the
   corresponding number. \hfill\mbox{[1 Mark]}
@@ -122,7 +122,7 @@
 to buy and when to sell this commodity. In the example above it should
 return the pair $\texttt{(1, 3)}$ because at index $1$ the price is lowest and
 then at index $3$ the price is highest. Note the prices are given as
-lists of \texttt{Float}s.\newline \mbox{} \hfill[1 Mark]
+lists of \texttt{Double}s.\newline \mbox{} \hfill[1 Mark]
 
 \item[(2)] Write a function that requests a comma-separated value (CSV) list
   from the Yahoo websevice that provides historical data for stock
@@ -183,13 +183,13 @@
 
 \subsection*{Advanced Part 3 (3 Marks)}
 
-A purely fictional character named Mr T.~Drump inherited in 1978
-approximately 200 Million Dollar from his father. Mr Drump prides
+A purely fictional character named Mr T.~Drumb inherited in 1978
+approximately 200 Million Dollar from his father. Mr Drumb prides
 himself to be a brilliant business man because nowadays it is
 estimated he is 3 Billion Dollar worth (one is not sure, of course,
-because Mr Drump refuses to make his tax records public).
+because Mr Drumb refuses to make his tax records public).
 
-Since the question about Mr Drump's business acumen remains, let's do a
+Since the question about Mr Drumb's business acumen remains open, let's do a
 quick back-of-the-envelope calculation in Scala whether his claim has
 any merit. Let's suppose we are given \$100 in 1978 and we follow a
 really dump investment strategy, namely:
@@ -212,7 +212,7 @@
 \end{itemize}\medskip  
 
 \noindent
-\textbf{Tasks (file drump.scala):}
+\textbf{Tasks (file drumb.scala):}
 
 \begin{itemize}
 \item[(1.a)] Write a function that queries the Yahoo financial data
@@ -310,7 +310,7 @@
 turn out to be a blue chip company.  Also, since the portfolios are
 chosen from the current S\&P 500, they do not include the myriad
 of companies that went bust or were de-listed over the years.
-So where does this leave our fictional character Mr T.~Drump? Well, given
+So where does this leave our fictional character Mr T.~Drumb? Well, given
 his inheritance, a really dumb investment strategy would have done
 equally well, if not much better.
 \end{document}
diff -r 6253f4681451 -r a7afc2540a88 progs/drumb.scala
--- a/progs/drumb.scala	Wed Nov 09 15:07:23 2016 +0000
+++ b/progs/drumb.scala	Thu Nov 10 00:15:14 2016 +0000
@@ -1,5 +1,5 @@
-// Advanvced Part 3 about Mr T. Drumb investing into stocks
-//==========================================================
+// Advanvced Part 3 about really dump investing strategy
+//=======================================================
 
 //two test portfolios
 
@@ -8,34 +8,55 @@
                             "DLR", "EQIX", "EQR", "ESS", "EXR", "FRT", "GGP", "HCP") 
 
 
-def get_yahoo_page(url: String): Option[List[String]] = ...
+// (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)
+
 
-//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)
 
diff -r 6253f4681451 -r a7afc2540a88 progs/drumb_sol.scala
--- a/progs/drumb_sol.scala	Wed Nov 09 15:07:23 2016 +0000
+++ b/progs/drumb_sol.scala	Thu Nov 10 00:15:14 2016 +0000
@@ -1,5 +1,5 @@
-// Advanvced Part 3 about Mr T. Drumb investing into stocks
-//==========================================================
+// Advanvced Part 3 about really dump investing strategy
+//=======================================================
 
 //two test portfolios
 
@@ -7,6 +7,12 @@
 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.
 
 import io.Source
 import scala.util._
@@ -25,13 +31,24 @@
   data.map(_.last.split(",").toList(6).toDouble)
 }
 
+
+// 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]]] = 
   for (year <- years.toList) yield
     for (symbol <- portfolio) yield get_first_price(symbol, year)
 
-get_prices(List("GOOG", "AAPL"), 2010 to 2012)
+
+// 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] = {
   (price_old, price_new) match {
     case (Some(x), Some(y)) => Some((y - x) / x)
@@ -43,6 +60,19 @@
   for (i <- (0 until (data.length - 1)).toList) yield 
     for (j <- (0 until (data(0).length)).toList) yield get_delta(data(i)(j), data(i + 1)(j))
 
+
+// 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 = {
   val somes = data(year).flatten
   val somes_length = somes.length
@@ -53,6 +83,9 @@
   }
 }
 
+//test case
+//yearly_yield(d, 100, 0)
+
 def compound_yield(data: List[List[Option[Double]]], balance: Long, year: Int): Long = {
   if (year >= data.length) balance else {
     val new_balance = yearly_yield(data, balance, year)
@@ -60,15 +93,13 @@
   }
 }
 
-val p = get_prices(List("GOOG", "AAPL"), 2010 to 2012)
-val d = get_deltas(p)
-yearly_yield(d, 100, 0)
-
 def investment(portfolio: List[String], years: Range, start_balance: Long): Long = {
   compound_yield(get_deltas(get_prices(portfolio, years)), start_balance, 0)
 }
 
 
+//test cases for the two portfolios given above
+
 println("Real data: " + investment(rstate_portfolio, 1978 to 2016, 100))
 println("Blue data: " + investment(blchip_portfolio, 1978 to 2016, 100))
 
diff -r 6253f4681451 -r a7afc2540a88 progs/lecture1.scala
--- a/progs/lecture1.scala	Wed Nov 09 15:07:23 2016 +0000
+++ b/progs/lecture1.scala	Thu Nov 10 00:15:14 2016 +0000
@@ -1,7 +1,7 @@
 // Lecture 1
 //===========
 
-// Assignments (values)
+// Value assignments
 // (variable names should be lower case)
 //======================================
 
@@ -32,7 +32,7 @@
 println("test")
 
 
-val tst = "This is a " + "test" 
+val tst = "This is a " ++ "test\n" 
 println(tst)
 
 val lst = List(1,2,3,1)
@@ -132,7 +132,6 @@
    ==     equals
    !      not
    && ||  and, or
-   
 */
 
 
@@ -141,23 +140,43 @@
 
 fact2(150)
 
+
 def fib(n: Int): Int =
   if (n == 0) 1 else
-    if (n == 1) 1 else fib(n - 1) + f(n - 2)
+    if (n == 1) 1 else fib(n - 1) + fib(n - 2)
 
 
-//a recursive function
-def gcd(x: Int, y: Int): Int = 2 //??? 
+//gcd - Euclid's algorithm
+
+def gcd(a: Int, b: Int): Int =
+  if (b == 0) a else gcd(b, a % b)
+
+gcd(48, 18)
+
 
 // String Interpolations
 //=======================
 
+val n = 3
+println("The square of " + n + " is " + square(n) + ".")
+
+println(s"The square of ${n} is ${square(n)}.")
+
+
+
+def gcd_db(a: Int, b: Int): Int = {
+  println(s"Function called with ${a} and ${b}.")
+  if (b == 0) a else gcd_db(b, a % b)
+}
+
+gcd_db(48, 18)
+
 
 // Assert/Testing
 //================
 
-// For-Maps (not For-Loops)
-//==========================
+// For-Comprehensions (not For-Loops)
+//====================================
 
 for (n <- (1 to 10).toList) yield square(n)
 
@@ -165,10 +184,19 @@
      m <- (1 to 10).toList) yield m * n
 
 
-val mtable = for (n <- (1 to 10).toList; 
-                  m <- (1 to 10).toList) yield m * n
+val mult_table = 
+  for (n <- (1 to 10).toList; 
+       m <- (1 to 10).toList) yield m * n
+
+mult_table.sliding(10,10).mkString("\n")
+
 
-mtable.sliding(10,10).mkString("\n")
+// with patterns
+
+for ((m, n) <- List((1, 4), (2, 3), (3, 2), (4, 1))) yield m + n 
+
+for (p <- List((1, 4), (2, 3), (3, 2), (4, 1))) yield p._1 + p._2 
+
 
 
 // Webpages
diff -r 6253f4681451 -r a7afc2540a88 slides/slides01.pdf
Binary file slides/slides01.pdf has changed
diff -r 6253f4681451 -r a7afc2540a88 slides/slides01.tex
--- a/slides/slides01.tex	Wed Nov 09 15:07:23 2016 +0000
+++ b/slides/slides01.tex	Thu Nov 10 00:15:14 2016 +0000
@@ -115,7 +115,7 @@
     \textcolor{codegreen}{\texttt{List[(BigInt, String)]}} &
                                       lists of BigInt-String\\
                                       & pairs\\
-    \textcolor{codegreen}{\texttt{List[List[Int]]}} & list of lists\\                                  
+    \textcolor{codegreen}{\texttt{List[List[Int]]}} & list of lists of Int's\\                                  
   \end{tabular}
   \end{center}