You can order nine kinds of cocktails at the bar. Yet there seems to be only eight cocktails on the drinks menu. Can you find out the ninth kind of cocktail that is hidden in the drinks menu?

Assignment

A drinks menu is a text file with UTF-8² character encoding that contains prices for a list of cocktails. This is an example drinks menu that corresponds to the image in the introduction (cocktails.txt³):

Black Russian...............€31,88
Bramble.....................€96,51
Cosmopolitan...............€168,69
Cuba libre.................€320,44
Mary Pickford...............€24,56
Sex on the beach...........€257,09
Suffering bastard..........€528,86
Tuxedo.......................€9,68

Each line of the text file contains the description of a cocktail. The description starts with the name of the cocktail, which never contains any dots (.). This is followed by one or more dots (.), a euro symbol (€) and the price of the cocktail. The price is always represented with two digits after a decimal comma (,). A drinks menu never contains cocktails that have the same two digits after the decimal comma in their price.

Your task is to extract the name of the hidden cocktail from a drinks menu. This is done in the following way:

• Write a function read_cocktail that takes the description of a cocktail (str). The function must return a tuple with three elements from the description of the cocktail: i) the name (str), ii) the number before the decimal comma (int) in the price and iii) the number after the decimal comma (int) in the price.

• Write a function read_menu that takes the location (str) of a drinks menu. The function must return a list containing for each cocktail on the drinks menu a tuple with three elements from the description of the cocktail: i) the name (str), ii) the number before the decimal comma (int) in the price and iii) the number after the decimal comma (int) in the price. These tuples must be listed in ascending order by the number after the decimal comma in the price.

• Write a function mask that takes two arguments: i) the name of a cocktail and ii) the number before the decimal comma (int) in the price of the cocktail. The function must return a string (str) with the reverse binary representation of the number, filled with zeros at the end until it has the same length as the name of the cocktail.

  Tip

  Use the built-in functions bin()⁴ or format()⁵ to determine the binary representation (str) of a decimal integer (int).

• Write a function select that takes two arguments: i) the name of a cocktail and ii) the number before the decimal comma (int) in the price of the cocktail. The function must return a string (str) containing the characters that are selected from the name of the cocktail to obtain the hidden cocktail in a drinks menu.

• Write a function extract that takes the location (str) of a drinks menu. The function must return the name (str) of the hidden cocktail in the drinks menu.

Example

In the following interactive session we assume that the text file cocktails.txt⁶ is located in the current directory.

>>> read_cocktail('Black Russian...............€31,88')
('Black Russian', 31, 88)
>>> read_cocktail('Cosmopolitan...............€168,69')
('Cosmopolitan', 168, 69)

>>> read_menu('cocktails.txt7')
[('Sex on the beach', 257, 9), ('Cuba libre', 320, 44), ('Bramble', 96, 51), ('Mary Pickford', 24, 56), ('Tuxedo', 9, 68), ('Cosmopolitan', 168, 69), ('Suffering bastard', 528, 86), ('Black Russian', 31, 88)]

>>> mask('Black Russian', 31)
'1111100000000'
>>> mask('Cosmopolitan', 168)
'000101010000'

>>> select('Black Russian', 31)
'Black'
>>> select('Cosmopolitan', 168)
'mpl'

>>> extract('cocktails.txt8')
'Shirley Temple Black'

Epilogue

Shirley Jane Temple⁹ (April 23, 1928 – February 10, 2014) was an American actress and diplomat. As a child with a diminutive stature, sparkling eyes, dimpled smile, and fifty-six blond curls, she became one of the most famous child stars in film history. Between 1932 and 1949 she appeared in more than fifty American movies and remains the youngest ever winner of an Academy Juvenile Award¹⁰. As an adult she adopted the name Shirley Temple Black and built a successful career as an ambassador.

Her name is further immortalized by the mocktail named after her: the Shirley Temple¹¹. This non-alcoholic mixed drink is traditionally made with ginger ale and a splash of grenadine, garnished with a maraschino cherry¹². It is often served to children dining with adults in lieu of real cocktails. If dark rum is added, it is called a Sherley Temple Black¹³ as an homage to her married surname.