14 Make sure the files you submit can be processed by just calling

    14 \bigskip

    15 \texttt{scala <<filename.scala>>}.\bigskip

    15 

    16 

    16 \noindent

    17 \noindent

    17 \textbf{Important:}

    18 \textbf{Important:} Do not use any mutable data structures in your

    18 

    19 \begin{itemize}

    20 \item Make sure the files you submit can be processed by just calling\\

    21 \mbox{\texttt{scala <<filename.scala>>}} on the commandline.

    22 

    23 \item Do not use any mutable data structures in your

    20 \texttt{ListBuffer}s, for example. Do not use \texttt{return} in your

    25 \texttt{ListBuffer}s, for example. 

    21 code! It has a different meaning in Scala, than in Java.

    26 

    22 Do not use \texttt{var}! This declares a mutable variable. ??? Make sure the

    27 \item Do not use \texttt{return} in your code! It has a different

    23 functions you submit are defined on the ``top-level'' of Scala, not

    28   meaning in Scala, than in Java.

    24 inside a class or object. Also note that the running time of

    29 

    25 each part will be restricted to a maximum of 360 seconds on my laptop.

    30 \item Do not use \texttt{var}! This declares a mutable variable. Only

    31   use \texttt{val}!

    32 

    33 \item Do not use any parallel collections! No \texttt{.par} therefore!

    34   Our testing and marking infrastructure is not set up for it.

    35 \end{itemize}

    36 

    37 \noindent

    38 Also note that the running time of each part will be restricted to a

    39 maximum of 360 seconds on my laptop.

    31 your own effort. You have not copied from anyone else. An

    45 your \textbf{own} effort. You have not copied from anyone else. An

    91   $1$ million. \hfill[2 Marks]

   104   $1$ Million. \hfill[2 Marks]

   111 \item 1 to 1 million where $837,799$ takes 525 steps

   124 \item 1 to 1 Million where $837,799$ takes 525 steps

   113 \end{itemize}\bigskip

   126 \end{itemize}

   114   

   127   

   115 

   128 \noindent

   116 

   129 \textbf{Hints:} useful math operators: \texttt{\%} for modulo; useful

   117 \subsection*{Part 2 (4 Marks)}

   130 functions: \mbox{\texttt{(1\,to\,10)}} for ranges, \texttt{.toInt},

   118 

   131 \texttt{.toList} for conversions, \texttt{List(...).max} for the

   119 This part is about list processing---it's a variant of

   132 maximum of a list, \texttt{List(...).indexOf(...)} for the first index of

   120 ``buy-low-sell-high'' in Scala. It uses the online financial data

   133 a value in a list.

   121 service from Yahoo.\bigskip 

   134 

   122 

   135 

   123 \noindent

   136 

   124 \textbf{Tasks (file trade.scala):}

   137 \subsection*{Part 2 (3 Marks)}

   125 

   138 

   126 \begin{itemize}

   139 This part is about web-scraping and list-processing in Scala. It uses

   127 \item[(1)] Given a list of prices for a commodity, for example

   140 online data about the per-capita alcohol consumption for each country

   128 

   141 (per year?), and a file with the data about the population size of

   129 \[

   142 each country.  From this data you are supposed to estimate how many

   130 \texttt{List(28.0, 18.0, 20.0, 26.0, 24.0)}

   143 litres of pure alcohol are consumed worldwide.\bigskip

   131 \]

   144 

   132 

   145 \noindent

   133 \noindent

   146 \textbf{Tasks (file alcohol.scala):}

   134 you need to write a function that returns a pair of indices for when

   147 

   135 to buy and when to sell this commodity. In the example above it should

   148 \begin{itemize}

   136 return the pair $\texttt{(1, 3)}$ because at index $1$ the price is lowest and

   149 \item[(1)] Write a function that given an URL requests a

   137 then at index $3$ the price is highest. Note the prices are given as

   150   comma-separated value (CSV) list.  We are interested in the list

   138 lists of \texttt{Double}s.\newline \mbox{} \hfill[1 Mark]

   151   from the following URL

   139 

   140 \item[(2)] Write a function that requests a comma-separated value (CSV) list

   141   from the Yahoo websevice that provides historical data for stock

   142   indices. For example if you query the URL

   145 \url{http://ichart.yahoo.com/table.csv?s=GOOG}

   154   \url{https://raw.githubusercontent.com/fivethirtyeight/data/master/alcohol-consumption/drinks.csv}

   148 \noindent where \texttt{GOOG} stands for Google's stock market symbol,

   157 \noindent Your function should take a string (the URL) as input, and

   149 then you will receive a CSV-list of the daily stock prices since

   158 produce a list of strings as output, where each string is one line in

   150 Google was listed. You can also try this with other stock market

   159 the corresponding CSV-list.  This list should contain 194 lines.\medskip

   151 symbols, for instance AAPL, MSFT, IBM, FB, YHOO, AMZN, BIDU and so

   160 

   152 on. 

   161 \noindent

   153 

   162 Write another function that can read the file \texttt{population.csv}

   154 This function should return a List of strings, where each string

   163 from disk (the file is distributed with the coursework). This

   155 is one line in this CVS-list (representing one day's

   164 function should take a string as argument, the file name, and again

   156 data). Note that Yahoo generates its answer such that the newest data

   165 return a list of strings corresponding to each entry in the

   157 is at the front of this list, and the oldest data is at the end.

   166 CSV-list. For \texttt{population.csv}, this list should contain 216

   158 \hfill[1 Mark]

   167 lines.\hfill[1 Mark]

   159 

   168 

   160 \item[(3)] As you can see, the financial data from Yahoo is organised in 7 columns,

   169 

   161 for example

   170 \item[(2)] Unfortunately, the CSV-lists contain a lot of ``junk'' and we

   162 

   171   need to extract the data that interests us.  From the header of the

   163 {\small\begin{verbatim}

   172   alcohol list, you can see there are 5 columns

   164 Date,Open,High,Low,Close,Volume,Adj Close

   173   

   165 2016-11-04,750.659973,770.359985,750.560974,762.02002,2126900,762.02002

   174   \begin{center}

   166 2016-11-03,767.25,769.950012,759.030029,762.130005,1914000,762.130005

   175     \begin{tabular}{l}

   167 2016-11-02,778.200012,781.650024,763.450012,768.700012,1872400,768.700012

   176       \texttt{country (name),}\\

   168 2016-11-01,782.890015,789.48999,775.539978,783.609985,2404500,783.609985

   177       \texttt{beer\_servings,}\\

   169 ....

   178       \texttt{spirit\_servings,}\\

   170 \end{verbatim}}

   179       \texttt{wine\_servings,}\\

   171 

   180       \texttt{total\_litres\_of\_pure\_alcohol}

   172 \noindent

   181     \end{tabular}  

   173 Write a function that ignores the first line (the header) and then

   182   \end{center}

   174 extracts from each line the date (first column) and the Adjusted Close

   183 

   175 price (last column). The Adjusted Close price should be converted into

   184   \noindent

   176 a \texttt{Double}. So the result of this function is a list of pairs where the

   185   Write a function that extracts the data from the first column,

   177 first components are strings (the dates) and the second are doubles

   186   the country name, and the data from the fifth column (converted into

   178 (the adjusted close prices).\newline\mbox{}\hfill\mbox{[1 Mark]}

   187   a \texttt{Double}). For this go through each line of the CSV-list

   179 

   188   (except the first line), use the \texttt{split(",")} function to

   180 \item[(4)] Write a function that takes a stock market symbol as

   189   divide each line into an array of 5 elements. Keep the data from the

   181   argument (you can assume it is a valid one, like GOOG or AAPL). The

   190   first and fifth element in these arrays.\medskip

   182   function calculates the \underline{dates} when you should have

   191 

   183   bought the corresponding shares (lowest price) and when you should

   192   \noindent

   184   have sold them (highest price).\hfill\mbox{[1 Mark]}

   193   Write another function that processes the population size list. This

   185 \end{itemize}

   194   is already of the form country name and population size.\footnote{Your

   186 

   195     friendly lecturer already did the messy processing for you from the

   187 \noindent

   196   Worldbank database, see \url{https://github.com/datasets/population/tree/master/data}.} Again, split the

   188 \textbf{Test Data:}

   197   strings according to the commas. However, this time generate a

   189 In case of Google, the financial data records 3077 entries starting

   198   \texttt{Map} from country names to population sizes.\hfill[1 Mark]

   190 from 2004-08-19 until 2016-11-04 (which is the last entry on the day

   199 

   191 when I prepared the course work...namely on 6 November; remember stock

   200 \item[(3)] In (2) you generated the data about the alcohol consumption

   192 markets are typically closed on weekends and no financial data is

   201   per capita for each country, and also the population size for each

   193 produced then; also I did not count the header line). The lowest

   202   country. From this generate next a sorted(!) list of the overall

   194 shareprice for Google was on 2004-09-03 with \$49.95513 per share and the

   203   alcohol consumption for each country. The list should be sorted from

   195 highest on 2016-10-24 with \$813.109985 per share.\bigskip

   204   highest alcohol consumption to lowest. The difficulty is that the

   205   data is scrapped off from ``random'' sources on the Internet and

   206   annoyingly the spelling of some country names does not always agree in the

   207   lists. For example the alcohol list contains

   208   \texttt{Bosnia-Herzegovina}, while the population writes this country as

   209   \texttt{Bosnia and Herzegovina}. In your sorted

   210   overall list include only countries from the alcohol list, whose

   211   exact country name is also in the population size list. This means

   212   you can ignore countries like Bosnia-Herzegovina from the overall

   213   alcohol consumption. There are 177 countries where the names

   214   agree. The UK is ranked 10th on this list with

   215   consuming 671,976,864 Litres of pure alcohol each year.\medskip

   216   

   217   \noindent

   218   Finally, write another function that takes an integer, say

   219   \texttt{n}, as argument. You can assume this integer is between 0

   220   and 177.  The function should use the sorted list from above.  It returns

   221   a triple, where the first component is the sum of the alcohol

   222   consumption in all countries (on the list); the second component is

   223   the sum of the \texttt{n}-highest alcohol consumers on the list; and

   224   the third component is the percentage the \texttt{n}-highest alcohol

   225   consumers feast on with respect to the the world consumption. You will

   226   see that according to our data, 164 countries (out of 177) gobble up 100\%

   227   of the world alcohol consumption.\hfill\mbox{[1 Mark]}

   228 \end{itemize}

   229 

   230 \noindent

   231 \textbf{Hints:} useful list functions: \texttt{.drop(n)},

   232 \texttt{.take(n)} for dropping or taking some elements in a list,

   233 \texttt{.getLines} for separating lines in a string;

   234 \texttt{.sortBy(\_.\_2)} sorts a list of pairs according to the second

   235 elements in the pairs---the sorting is done from smallest to highest;

   236 useful \texttt{Map} functions: \texttt{.toMap} converts a list of

   237 pairs into a \texttt{Map}, \texttt{.isDefinedAt(k)} tests whether the

   238 map is defined at that key, that is would produce a result when

   239 called with this key.

   240 

   241 \newpage

   205 Since the question about Mr Drumb's business acumen remains, let's do a

   251 Since the question about Mr Drumb's business acumen remains open,

   206 quick back-of-the-envelope calculation in Scala whether his claim has

   252 let's do a quick back-of-the-envelope calculation in Scala whether his

   207 any merit. Let's suppose we are given \$100 in 1978 and we follow a

   253 claim has any merit. Let's suppose we are given \$100 in 1978 and we

   208 really dumb investment strategy, namely:

   254 follow a really dumb investment strategy, namely:

   223 \item We do this for 38 years until January 2016 and check what would

   269 \item We do this for 38 years until January 2017 and check what would

   225 \end{itemize}\medskip  

   271 \end{itemize}

   272 

   273 

   274 \medskip