CPSC/DATA 350 — Applications of Databases — Fall 2024

Assignment #0 — Python practice

Possible experience: +25XP

Due: Mon Sep 9th Wed Sep 11, midnight

Overview

This assignment simply guides you towards getting up to speed in Python so you can perform competently in CPSC/DATA 350.

Installing Python

Ian has installed Python on the cpsc.umw.edu server. Make sure you can connect to the server, as you did in CPSC 225 (see Ian's notes if you need a refresher on how to do that). When you're logged in, type this on the command line:

$ python3

and make sure you get some output followed by a prompt with a triple-wakka: ">>>". If you don't, email me right away with whatever error message you get. Otherwise, quit the Python console by typing "CTRL-D".

Learning Python

If you're new to Python (or even if you're not) go to the official Python tutorial, and make sure that the version number in the drop-down box at the top matches what's on the cpsc server (3.10 as of this writing). Then, grab a coffee, and actually read the following sections:

(I'm not discouraging you from reading any of the other sections as well if you're interested. You could even make use of that material in various projects this semester. The above is a "must have" list, though. If you know those sections, I think that's a minimally sufficient set and you'll be good to go for this semester.)

Getting some practice

Setting up the pythonpractice.py test script

The file pythonpractice.py contains some little practice exercises. Copy it to your cpsc.umw.edu account by typing this command at the cpsc prompt:

$ wget  http://stephendavies.org/pythonpractice.py

and verify that it downloaded a copy of this file into your cpsc server directory.

Now use vim to create a file in the same directory called "yourumwnetid_pythonpractice.py" with nothing in it but a single comment line. (Please do not call the file anything else. Please do not get creative by using a shorter name, or a longer one, or changing the capitalization, or omitting the underscore, or using a dash instead of an underscore, or anything else. Thanks. Also, in case it's not clear, you shouldn't literally call the file "yourumwnetid_pythonpractice.py". Instead, you should substitute your UMW Net ID. For instance, "jbieber2_pythonpractice.py" would be a correct filename.)

Now run things with the command:

$ python3  pythonpractice.py  yourumwnetid

(Again, just to be super clear, you need to substitute your UMW Net ID for the word yourumwnetid in the command above. So "python3 pythonpractice.py jbieber2" would be a reasonable thing to type.)

Verify that the output you get is:

You've earned 0/25 XP!

Then take a break and stretch your legs.

Writing your practice code

Okay, now open up your yourumwnetid_pythonpractice.py file in vim, and add the following variables and functions:

  1. A variable called HAL whose value is the integer 9000.
  2. A variable called L whose value is a list containing the integer 3.
  3. A variable named BB whose value is the string containing only the digit 8.
  4. A variable called R2 whose value is a list with elements D and 2, both strings.
  5. A variable named WALL which is a list of one element. That element is also a list. That (internal) list contains one element: the string with the letter E.
  6. A variable named K which is a set with one element: the string 2SO.
  7. A variable named C which is a list with one element. That element is a set whose only element is the string "3PO".
  8. A set called Poppins that contains all the unique lower-case letters from the string "supercalifragilisticexpialidocious". (You should be able to do this without having to sift through the word and manually compute all the duplicates by hand yourself.)
  9. A dictionary Galactica that contains the following key/value pairs (all strings):
    10. KeyValue
    KaraStarbuck
    LeeApollo
    LouanneKat
  10. After creating your Galactica dictionary with the above three key/value pairs, add code using the [] notation that adds the following additional three key/value pairs to it:
    11. KeyValue
    KarlHelo
    SharonBoomer
    MargeRacetrack
  11. Then, after adding those three additional key/value pairs to it, delete the pilot with call sign "Kat" (real name Louanne) from the dictionary.(
  12. A variable Wheel which is a dictionary with strings as keys and lists as values. Begin by adding these keys and values to it:
    13. KeyValues (in list)
    BlueMoiraine, Siuan
    GreenAlanna
    Purple(nothing)
    WhiteSarene
    Yellow(nothing)
    Plaid(nothing)
    RedElaida, Liandrin
  13. Then, after creating your Wheel dictionary with the above values, write code to make the following changes to it:
    1. Add a new key value pair: the key should be Brown and the value should be a list with Verin, Saerin, and Janya, in that order.
    2. Append the string Egweyne to the end of the Green list.
    3. Remove Liandrin from the Red list.
    4. Add Nynaeve to the Yellow list.
    5. Delete the Plaid key/value pair altogether.
  14. A variable Germanna_levels that contains a list of the two strings Freshman and Sophomore.
  15. A variable UMW_levels that contains a list of the four strings Freshman, Sophomore, Junior, and Senior.
  16. A variable MaryWash_levels which refers to the same list that UMW_levels refers to.
  17. A variable CNU_levels which, although referring to a list with the identical contents as the UMW_levels list, is nevertheless a different list object.
  18. A one-argument function called plus2 that takes a numeric argument and returns that argument added to the number 2.
  19. A function called gimme_dat_set that takes no arguments and returns a set containing the strings Pris, Leon, and Roy. Each time gimme_dat_set() is called, it should return the same set object.
  20. A function called gimme_set_like_dat that takes no arguments and returns a set containing the strings Neo, Morpheus, and Trinity. Unlike gimme_dat_set(), every time gimme_set_like_dat() is called it should return a different set object (with the same contents).
  21. A function center that takes one argument, a string. If that string is the empty string, center should return None. If the argument has an odd number of letters, the function should return the one in the exact middle. If the argument has an even number of letters (greater than 0), the function should a string with the two middle ones. (For example, calling the function with the value "Optimus" should return the string "i", whereas calling it with "Terminator" should return the value "in".)
  22. A function nuke_last which takes two arguments, a list and an item. The function should modify the passed list in place to remove the last entry matching the element. If the item passed is not in the list, the function should do nothing. (For example, if a variable "droids" has the value [ 'R', 2, 'D', 2, 'C', 3, 'P', 'O' ]", then after calling the function with droids and 2, the variable should have the contents [ 'R', 2, 'D', 'C', 3, 'P', 'O' ]".) The function need return nothing.
  23. A function middlest that takes three (numeric) arguments, and returns the value of the middle one in numerical order. (For example, middlest(5,7,2) should return 5. In case of ties, do what's obvious.)
  24. A function tack_on_end that takes three arguments, the last one optional. Argument #1 is a list. Argument #2 may be either a list or an atomic type (like a string or integer). The function should add either the elements of argument #2, in order (if argument #2 is a list), or argument #2 itself (if argument #2 is anything else) to the end of argument #1. It should do this a number of times equal to the third argument, whose default value should be 1. (For example, suppose a variable "colonies" has the value ['Caprica','Scorpia','Gemenon']. If tack_on_end(colonies,['Aerelon','Libris']) is called, colonies should then have the value ['Caprica','Scorpia','Gemenon','Aerelon','Libris']. Then, if tack_on_end(colonies,'Aquaria',4]) is called, colonies should have the value ['Caprica','Scorpia','Gemenon','Aerelon','Libris','Aquaria','Aquaria','Aquaria','Aquaria'].) The function need return nothing.
  25. A function wondrous_count that takes one integer, and returns the number of steps required to reach 1 from that number in a Collatz sequence. The Collatz Conjecture (never yet proven) postulates the following. Take any positive integer. If it is even, divide it in half. If it's odd, triple it and add one. Keep doing this until you get the number 1. The Collatz Conjecture hypothesizes that every number will eventually reach 1 this way. (Examples: wondrous_count(1) should return 0, wondrous_count(3) should return 7, wondrous_count(26) should return 10, and wondrous_count(27) should return 111.)
  26. A function unique_vals that takes a dictionary and returns a list (in any order) of the unique values of that dictionary. For instance, unique_vals({'Boomer':'cylon','Helo':'human','Apollo':'human'}) should return the list ['cylon','human'] (or ['human','cylon']).

Scoring yourself

Just run the program (even if you're not all the way done) and read the output to see which problems you've gotten right and which ones you still need to work on.

Turning it in

For this assignment, send me an email with subject line "CPSC/DATA 350 Python Practice turn-in" and with your yourumwnetid_pythonpractice.py file as an attachment. Note that this will require you to first download your Python file from cpsc.umw.edu to your own personal machine.

Getting help

I'm happy to answer questions and give hints! Come to office hours, or send me email with subject line "CPSC/DATA 350 Python practice help!!"