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Assignment #3
CS1026 – Summer 2021
1
CS1026 – Assignment #3
Country Classes
Due: Thursday, June 10, 11:55pm on OWL
Weight: 16%
Learning Outcomes
By completing this assignment, you will gain skills relating to:
• strings and text files;
• writing and using your own classes;
• using complex data structures (i.e., lists, sets, dictionaries);
• testing code and developing test cases;
• adhering to specifications.
Task
Data files are very common in many disciplines. They form the input for a variety of
different kinds of processing, analysis, summaries, etc. An associated problem is to
maintain these data files – to add information, update or correct information. Manually
updating data files can be tedious and can lead to errors. A common approach is to
use a program – an update program that takes a data file and a file of updates and
then creates a new version of the data file with the updates applied.
In this assignment you will create a complete program that will update an existing data
file containing information about countries. The tasks are outlined below.
Functional Requirements/Specifications
Task 1
Implement a class Country that holds the information about a single country.
The file that holds this class will be named country.py and will contain the
following:
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1. Instance Variables
§ name: the name of the country (string)
§ population: the population of the country (string)
§ area: the area of the country (string)
§ continent: the name of the continent to which the country belongs
(string)
Note: the instance variables population and area can be left as strings for
this assignment, as there are no computations involving either. The update
program just needs to update these values and save them to a file.
2. Methods
§ Constructor, __init__ (self, name, pop, area, continent)
§ Getter Methods: get_name, get_population, get_area, get_continent
§ Setter Methods: set_population, set_area, set_continent
§ def __repr__ (self): generates a string representation for class
objects
Example of output from __repr__
Test all of your classes and methods before moving to the next section. Feel free
to create other helper methods if necessary.
Task 2
Implement a class called CountryCatalogue; name the file catalogue.py. This
class will use a file to build the data structures to hold the information about
countries. The file data.txt contains information about a number of countries.
Name (pop: population value, size: area value) in Continent
e.g., Nigeria (pop: 11723456, size: 324935) in Africa
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1. Instance Variables
§ country_cat: this is a collection of countries. Each member is an
object of the class Country. The collection could be a set, dictionary
or list. It is important that the collection stores objects of type
Country.
§ You may add other instance variables as you see fit.
An example of the data.txt file is:
Notice that:
§ There is a header line: Country|Continent|Population|Area. This
tells you how the data is formatted in the file.
§ The file consists of records for each country – one per line, with the
information as described in the header line.
§ The different fields of each record are separated by vertical bars: |.
§ A field (except for country name) may be missing (see Columbia and
Egypt), but the record will still have the three vertical bars.
2. Methods
§ Constructor, __init__ (self, country_file): The constructor
method will take a single parameter (besides self) that is the name of
the file that contains the information about each country. The
constructor will use the data in the file to construct the data structure
country_cat. A sample data file has been provided: data.txt,
data2.txt and data3.txt. [Note: all files have headers, and
these files are meant for you to test your program; these may
NOT be the same files used to evaluate your solution.]
Country|Continent|Population|Area
Brazil|South America|213,952,606|8,515,767
Canada|North America|38,048,738|9,984,670
China|Asia|1,444,390,177|9,596,961
Colombia||50,372,424|1,141,748
Egypt|Africa|101,576,517|
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§ Setter Methods: set_country_population, set_country_area,
set_country_continent
§ find_country(self, country): Given a country object (that is, an
object of the Country class), this method checks to see if that country
object is in country_cat. If it is, it just returns the country object, but
if it is not, it returns the null object: None.
§ add_country(self, country_name, pop, area, cont): Given the
name, population, area and continent of a country, this method adds
a new country to country_cat; it should only be added if the country
does not already exist in country_cat. The method should return
True if the operation is successful (country successfully added), or
False if it is not (e.g., the country you entered already exists in the
catalogue).
§ print_country_catalogue(self): This method prints a list of the
countries and their information to the screen; it should make use of
the repr method of the Country class.
§ save_country_catalogue(self, fname): This method will enable
all the country information in the catalogue to be saved to a file. The
method takes as a parameter the name of the file. All the countries
should be sorted alphabetically by name (A – Z) prior to saving. If the
operation is successful, the method should return the number of
items written; otherwise, it should return a value of -1. The file
should appear in the exact same format as the original file,
namely:
§ You may add other methods as you see fit.
Country|Continent|Population|Area
Brazil|South America|213,952,606|8,515,767
Canada|North America|38,048,738|9,984,670
China|Asia|1,444,390,177|9,596,961
Colombia|South America|50,372,424|1,141,748
Egypt||101,576,517|1,010,408
Indonesia||260,581,345|
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Notice that:
§ There should be no spaces between the fields and vertical bars.
§ If a field has no value, then nothing should be printed (e.g., see Egypt
and Indonesia with no continent value and Indonesia with no area
given).
Test all of your classes and methods before moving to the next section. Feel free
to create other helper methods if necessary.
Task 3
Implement a Python module, called process_updates.py, that has a function
process_updates(country_fname, update_fname). This function takes two
parameters: the first parameter will be the name of a file containing country data
(e.g., data.txt). The second file will contain the name of a file containing
updates. Each record in the update file specifies updates for a single country.
The format of a record in the update file is as follows:
Where an ‘update’ is of the form “L=value”, where L can be POP, for
population, AREA, for area, and CON, for continent. Updates are separated by
semicolons and a line can have 0, 1, 2 or 3 updates; any updates after the first
3 are simply ignored, and you need not worry about their values.
Valid values in an update are as follows:
§ For Population and Area, a valid value is a string of digits with
commas separating groups of 3. Examples of valid values are
“123,456”, “1,333,456”, “23,333,444”. Examples of invalid values are
“123456”, “123 345 555”, “123,344.44”.
§ For Continent, a valid value is one of the continents: “Africa”,
“Antarctica”, “Asia”, “Australia”, “Europe”, “North America” and
“South America”. The string of letters can be uppercase or lowercase,
and there may be more than one space between the “North” and
“America” and the “South” and the “America”. Once a valid
Country;update1;update2;update3
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continent is found, the first letter of the name or parts should be
capitalized, and there should only be 1 space between the “North”
and the “America” and the “South” and the “America”. For example,
“asia” should be stored as “Asia”, “aFRICA” should be stored as
“Africa”, “north America” should be stored as “North America”.
An example of an update file is:
Notice that:
§ The updates can be in different orders (e.g., the update for Vietnam is
area first, then population).
§ If a country is specified and that country is NOT already in the
catalogue, then that country and its attributes (at least the ones
specified; not all have to be specified) should be added to the
catalogue (again, any attributes beyond the first 3 are to be
ignored).
§ There can be spaces before and/or after either the semicolons or the
equal signs; these spaces can be ignored.
§ There can also be spaces in other places, such as in country names or
within numbers. These represent errors and could cause problems in
processing. You should treat these errors (do not try to fix them),
and they should be handled as exceptions (see below).
§ In the updates to France, for example, there are four updates; the last
update is simply ignored, and your program should only consider the
first three updates. As well, the first three updates to France contain
two updates for population. These are applied in order. This would
mean that the update POP=64,668,129 is applied, and then the
Brazil;POP=193,364,111;AREA=8,511,966
Indonesia;POP=260,581,345
Italy;POP=59,801,999
Japan;POP=127,380,555;AREA=377,800
Sweden;POP=9,995,345;AREA=450,295;CON=Europe
Vietnam;AREA=331,310;POP=95,541,921;CON=Asia
France;POP = 64,668,129;POP=65,668,150;AREA=541,666;CON=Europe
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update POP=64,668,150 is applied, essentially overwriting the first
update.
How process_updates() works:
As noted above, the function process_updates() gets two files as parameters.
The first parameter is the name of the file with the country data, and the second
parameter is the name of the file with the update data.
The country file should be processed first. The function process_updates()
should ensure that it exists. If it does exist, it should then proceed to process the
data file using the class CountryCatalogue. If the country file does not exist,
then process_updates() should give the user the option to quit or not
(prompts for “Y”(yes) or “N”(no)). If the user does not wish to quit (i.e., they
respond with “N”), then the function should prompt the user for the name of a
new file. If the user wishes to quite (i.e., responds with a “Y”, or anything other
than “N”), then the method should exit and return False. The method should
continue to prompt for file names until a valid file is found or the user quits.
If the user chooses to quit with no country file processed, then the function
process_updates() should NOT try to process the updates file. Instead, it
should write to the file output.txt the message “Update Unsuccessful\n” –
just this single line. It should then exit and return False.
If the function process_updates() has successfully processed the country
file, then it should proceed to process the file of updates. It should prompt the
user in a similar manner to how the country file was input (i.e., using a loop to
continuously prompt the user until a file is found that exists or until the user
quits).
If the user quits without an update file being selected, then the function
process_updates() should write to the file output.txt the message “Update
Unsuccessful\n” – just this single line. It should then exit and return False.
If an update file is found, then the function process_updates() should process
the updates (i.e., update the information about the countries and then output
the new updated list of countries in alphabetical order to the file output.txt.
The output should use the method save_country_catalogue(self, fname)
from the CountryCatalogue (see Task 2). It should then exit and return True.
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In processing the updates from the update file, the updates may have invalid
values (see above). If an update has an invalid value, then the entire line
should be skipped, and none of the updates should be processed. It is
difficult to anticipate all possible problems with the updates, and some may
cause your program to fail – that is, some invalid input MAY cause exceptions
when processing the line. Your program should be designed to catch any of
these exceptions and then print a message and skip all processing of that line.
The Python program main.py file is provided as the interface to your
program. It has been designed to prompt for the names of a country file and a
file of updates, and then it calls the function process_updates(); make sure
that you use the names of functions and methods as described above, or your
program may not function. You may use main.py to test your program in other
ways. As mentioned above, three data sets of countries have been provided
(data.txt, data2.txt and data3.txt), as well as three different files of
updates (upd.txt, upd2.txt and upd3.txt). These files can be found in
Resources > Assignment 3 on OWL. You may use these to test your program.
NOTE: while main.py will test some aspects of your program, it does not
do a complete and thorough testing – this is left up to you. A program
similar to, but different than, main.py will be used to test your program – it
will include other tests.
The following may be helpful in sorting data structures:

How to Sort a List, Tuple or Object (with sorted) in Python

How to Sort Python Dictionaries by Key or Value


Non-Functional Requirements/Specifications
1. Include brief comments in your code identifying yourself (i.e., include your name
in a comment at the beginning of your program), describing the program, and
describing key portions of the code.
2. Assignments are to be done individually and must be your own work. Software
may be used to detect academic dishonesty (cheating).
3. Use Python coding conventions and good programming techniques. Examples
include:
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§ meaningful variable names;
§ conventions for naming variables and constants (you can use underscores
or camel case, but be consistent);
§ readability – indentation, whitespace, consistency.
4. The name of the files you submit MUST be as follows:
§ country.py containing the class Country;
§ catalogue.py containing the class CountryCatalogue;
§ process_updates.py containing the function process_updates().
5. You will attach the files in OWL. DO NOT compress/zip them. DO NOT just
enter code into the text submission area on OWL.
6. Make sure to use Python 3.9 as the interpreter; failure to do so may result in the
testing program failing.
Marking the Assignment
1. Your program will be executed by an automated testing program. This testing
program assumes that:
§ The modules are named main.py, process_updates.py,
catalogue.py and country.py.
§ That you are using Python 3.8 or 3.9.
§ That you submitted via OWL correctly (i.e., NOT compressed).
2. The TAs will be looking at the following things when grading your assignment:
§ Are the modules, classes and functions named properly for testing?
§ Is there a program process_updates.py which has a function
process_updates()?
§ Does the program work with the test program, main.py?
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§ Is there an effective use of functions and methods?
§ Is the output according to specifications?
§ Is the code commented clearly? Does it contain meaningful names?
The TAs will also be checking to ensure that things were not hardcoded and that
your program actually uses the techniques learned in this course.