diff -r ecf83084e41d -r 87e55eb309ed progs/trade_sol.scala
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/progs/trade_sol.scala	Wed Nov 09 00:52:08 2016 +0000
@@ -0,0 +1,79 @@
+// Part 2 about Buy-Low-Sell-High using Yahoo Financial Data
+//===========================================================
+
+
+// (1) Complete the function that is given a list of floats
+// and calculuates the indices for when to buy the commodity 
+// and when to sell
+
+def trade_times(xs: List[Double]): (Int, Int) = {
+  val low = xs.min
+  val low_index = xs.indexOf(low)
+  val rest = xs.drop(low_index)
+  val high = rest.max
+  val high_index = rest.indexOf(high)
+  (low_index, low_index + high_index)
+}
+
+val prices = List(28.0, 18.0, 20.0, 26.0, 24.0)
+assert(trade_times(prices) == (1, 3), "the trade_times test fails")
+
+
+// (2) Complete the ``get webpage'' function that takes a
+// a stock symbol as argument and queries the Yahoo server
+// at
+//      http://ichart.yahoo.com/table.csv?s=<<insert stock symbol>>
+// 
+// This servive returns a CSV-list that needs to be separated into
+// a list of strings.
+
+import io.Source
+import scala.util._
+
+def get_yahoo_page(symbol: String): List[String] = {
+  val url = """http://ichart.yahoo.com/table.csv?s=""" + symbol
+  Try(Source.fromURL(url)("ISO-8859-1").getLines.toList).
+    getOrElse { println(s"  Problem with: $url"); List() }
+}
+
+// (3) Complete the function that processes the CSV list
+// extracting the dates and anjusted close prices. The
+// prices need to be transformed into Doubles.
+
+def process_page(symbol: String): List[(String, Double)] = {
+  get_yahoo_page(symbol).drop(1).map(_.split(",").toList).map((xs) => (xs(0), xs(6).toDouble))
+}
+
+
+// (4) Complete the query_company function that obtains the
+// processed CSV-list for a stock symbol. It should return
+// the dates for when to buy and sell the stocks of that company.
+
+def query_company(symbol: String): (String, String) = {
+  val list = process_page(symbol).reverse
+  val (tbuy, tsell) = trade_times(list.map(_._2))
+  (list(tbuy)._1, list(tsell)._1)
+}
+
+//query_company("GOOG")
+
+
+val indices = List("GOOG", "AAPL", "MSFT", "IBM", "FB", "YHOO", "AMZN", "BIDU")
+
+for (name <- indices) {
+  val times = query_company(name)
+  println(s"Buy ${name} on ${times._1} and sell on ${times._2}")
+}
+
+
+
+/*
+scala trade.scala 2> /dev/null || echo "command1 borked it"
+
+command1
+if [ $? -ne 0 ]; then
+    echo "command1 borked it"
+fi
+*/
+
+