PA05: Song Manager

CS 1112 - Intro to Programming

Due by: 11:00pm Wednesday, March 26th, 2024

PDF Instructions Starter Code

Objective:

The objective of this assignment for students is to learn how to work with lists, the nested list data structure, and tuples for a practical application. By the end of the assignment, students should be able to:

  • Navigate lists of lists
  • Retrieve from, and modify data in, a single list
  • Understand the similarities and differences between working with lists and tuples

Background: lists of lists

A list of lists is a list where each entry is a different list. If each component is a list of strings, for example, a list of those lists might look like the following:

foods_by_letter = [
['apple', 'almond', 'artichoke', 'asparagus'],
['basil', 'beef', 'bread', 'broccoli'],
['cashew', 'cherry', 'chickpea', 'chocolate']
]

Accesses to list elements can occur at “two levels”. For example:

print(foods_by_letter[0])

will print [‘apple’, ‘almond’, ‘artichoke’, ‘asparagus’], which is the entire element at index 0, not the string ‘apple’. The statement:

print(foods_by_letter[0][0])

however, will print ‘apple’ because this is the element: A) at index zero of the list which is B) at index zero of the entire list.

A list of lists is one example of a nested data structure, which is a data structure whose members are other data structures. More data structures offer more freedom in representing data: a list of lists is the way the song database is represented in this assignment, but it is entirely possible to represent the data in something like a dictionary with list elements or a similar setup.

2: Task

As a course staff, we listen to a lot of music. In fact, we listen to so much music that we have trouble keeping track of it! We want your help to manage a database of our favorite songs and retrieve relevant information about them.

In a file called song_manager.py, write a small library of functions to interact with this song database. The functions will include “helper functions” (smaller functions) and more involved functions which the helper functions will help (make easier to implement by reducing the code you have to write).

The song database is a list of lists. Each list is composed of strings corresponding to a person’s name as well as information about a favorite song of theirs. A short example of the database we will test your code with might look like the following:


database_list = [
['Paul', 'Sledgehammer', 'Peter Gabriel', 'So', 'Funk', '1986'],
['Sam', 'Never Gonna Give You Up', 'Rick Astley', 'Whenever You Need Somebody', 'Dance-pop', '1987'],
['Jordan', 'Brother Louie', 'Modern Talking', 'Ready for Romance', 'Dance-pop', '1986'],
# more entries go here...
]

The format of each list in the “database” (list of lists) is, in order,

[name, title, artist, album, genre, year]

To borrow from the full example above, an entry that is given as

[‘Paul’, ‘Sledgehammer’, ‘Peter Gabriel’, ‘So’, ‘Funk’, ‘1986’]

means that the person this entry corresponds to is ‘Paul’, that their favorite song is titled ‘Sledgehammer’, that the song is by artist ‘Peter Gabriel’, the song is from the album ‘So’, the song is a ‘Funk’ song, and the song is from ‘1986’.

In a Python file named song_manager.py, write a small library of functions that will interact with a “song database” that is a list of lists. We’ll have you write both “helper functions” (small functions to do specific tasks) and more involved functions that can be implemented using the helper functions.

For all functions, you do not need to worry about getting the full database list–you can use our small example in this document to test your code, but we will pass in our own database in the autograder. The format of each list in the database, which is described above, is constant. Be sure to also keep in mind the “two levels” of access for lists of lists as described in Section 1.

2.1 find_entry(database_list, person_name)

Given a string person_name, find the list within database_list whose first item (at index 0) matches person_name, and return that list. If there is no list within database_list with a name that matches person_name, return nothing.

For testing purposes, you do not need to worry about the possibility that multiple entries have names which match person_name; it is okay to only return the first match.

Example usage: given:

database_list = [
['Angela', 'Wurli', 'Dominic Fike', 'What Could Possibly Go Wrong', 'Alternative', '2020'],
['Evelyn', "You're My Best Friend", 'Queen', 'A Night at the Opera', 'Rock', '1976']
]

Calling find_entry(database_list, “Angela”) should return the entire list:


['Angela', 'Wurli', 'Dominic Fike', 'What Could Possibly Go Wrong', 'Alternative', '2020']

That is, all data for the favorite song of ‘Angela’ should be returned, and no data for the favorite songs of any other people in the list (such as ‘Evelyn’) should be returned.

2.2 add_entry(database_list, person_name, song_info)

Given a string person_name and a list of other data song_info, make a list with the two components that matches the given format, then add that combined list to database_list. This function should modify database_list in place but not return anything.

Example usage: given


database_list = [
['Angela', 'Wurli', 'Dominic Fike', 'What Could Possibly Go Wrong', 'Alternative', '2020'],
['Evelyn', "You're My Best Friend", 'Queen', 'A Night at the Opera', 'Rock', '1976']
]

Calling:

add_entry(database_list, "Paul", ['Sledgehammer', 'Peter Gabriel', 'So', 'Funk', '1986'])

should update database_list so that it now contains the lists (in some order ):

['Angela', 'Wurli', 'Dominic Fike', 'What Could Possibly Go Wrong', 'Alternative', '2020'],
['Evelyn', "You're My Best Friend", 'Queen', 'A Night at the Opera', 'Rock', '1976'],
['Paul', 'Sledgehammer', 'Peter Gabriel', 'So', 'Funk', '1986']

To interact well with other functions, we will not attempt to test your code by calling add_entry with the same argument person_name without removes in between. It does not matter where in the list you add the new entry so long as you can successfully retrieve that entry with a later find_entry call using the same person_name.

2.3 remove_entry(database_list, person_name)

Given a string person_name in the same manner as with find_entry and add_entry, update database_list to remove the list containing the song data for the person named person_name. If there is no entry with a name matching person_name, do nothing. Like with add_entry, this function should change the database database_list in place but not return anything.

HINT: one approach could be to use another function you’ve written for this assignment (though be sure to check the output!).

2.4 replace_by_name(database_list, person_name, new_info)

Given a string person_name (in the same format as above), replace the song data for person_name in database_list with the new data contained within new_info.

There are many possible approaches to this, including the use of other functions you write for this homework. Whether you, for example, do a “full remove” on the existing entry and add a new one, or change an existing entry in place, what we’ll look for is being able to see the new information we expect when we call find_entry on the same person_name after calling replace_by_name.

2.5 Helper functions

Each of these functions work with a specific list within the database that was previously described; that is, each of the following functions should work “directly” on a list of the following format or similar:

['Rob', 'On Top of the World', 'Imagine Dragons', 'Night Visions', '2013']

Each of these functions can be implemented in a very compact structure; in fact, it is probably preferable to do so.

2.5.1 get_favorite_song_name(song_info_list)

Given a list song_info_list of format described at the beginning of this subsection, return the name of the song (not the name of the person whose favorite song it is).

2.5.2 get_favorite_song_artist(song_info_list)

Given a list song_info_list of format described above, return the artist the song is by.

2.5.3 get_favorite_song_album(song_info_list)

Given a list song_info_list of format described above, return the album the song is from.

2.5.4 get_favorite_song_genre(song_info_list)

Given a list song_info_list of format described above, return the genre of the song.

2.5.5 get_favorite_song_year(song_info_list)

Given a list song_info_list of format described above, return the year the song was released in. Note: there is no need to return this as an int.

2.6 Reflection

In a separate PDF document (preferably using about 150-250 words total), answer the following two questions:

For each of the functions you implemented in this assignment, briefly describe A) whether the function can be used as-is using tuples instead of lists, OR B) what changes should be made to the function so that the function can be work ith tuples. Please provide feedback on this assignment to help guide the instructors when designing future homework assignments. Some areas to help guide you: was there too much work or not enough? Were instructions not detailed enough, or could they have been more brief? Do you feel this assignment was an effective way to apply what you learned in class? All feedback is appreciated, and specific feedback is encouraged. Keep the following in mind as you write your code, as you will be graded on these aspects:

  • Don’t forget your header at the top of your .py file (see section 2.1)
  • Cite your resources clearly or state you did not use any
  • Use appropriate variables names throughout your program
  • Include comments throughout your code to explain what you are doing (see example below:)
 foods = ['apple', 'pear'] # This is a list of foods (in-line comment)

Document all of your functions with docstrings (not just comments). Note that the following is what we are referring to:

def func(first_param, second_param):
'''
This is a docstring.
Description of the function - what it does
:param first_param: what is it's data type,
what does this parameter represent in the context of the function
:param second_param: what is it's data type,
what does this parameter represent in the context of the function
:return: what is the data type of the item being returned,
what does the item returned represent
'''

3 Submission and Collaboration Policy

3.1 Your Submission–Comment Header

Your .py file should contain the following information (header) at the top of your file:

# NAME: e.g I. Lv. Sneks
# COMPUTING ID: e.g. ils3py@virginia.edu
# PA NUMBER and NAME: e.g. PA## - Name of the Assignment
Resources used (if applicable):

For Resources, include URLs to any online resources where you studied or reviewed code that is specific to these problems, including any physical textbooks you referenced. Include any other resources you used here. Note on resources: Please feel free to refer to the lecture slides, demos, and in-class labs to complete this assignment, which can all be located on Canvas.

Absolutely no collaboration with any fellow students (who are not current CS 1112 course TAs) is allowed. Your work must represent individual effort. You must write your own code: not just type it, but also compose it yourself as your own original work.

You must cite any and every source you consult, other than those explicitly provided by the course itself. If you work with, obtain or receive help from another source (Internet website, textbook, TA, tutor, online video, etc.), nothing should be copied or retyped into the submitted solution. References must be documented in a comment in the code on the assignment. Any copied work is an Honor Code violation.

Gradescope

Submitting on Gradescope

  1. Go to Gradescope (linked in Canvas course website)

  2. Click on PA05 – Song Manager in the assignment list on Gradescope

  3. Upload your Python program as song_manager.py.

  4. Write your reflection in a separate document and save/download it as a PDF (please ask us if you are unsure how to save your file in PDF format. We are happy to help!)

  5. Submit to the same Gradescope assignment PA05 – Song Manager

  6. Ensure you have uploaded two (2) files before you submit!

Note: If you face any difficulties or have questions, please reach out to the instructor or teaching assistants for assistance.