DEV Community: Milnor

Training a Snake to Clean my Desktop

Milnor — Wed, 17 May 2023 18:36:39 +0000

The Task

The final project in the Coding Nomads Python 101 course is to write (1) a Python script that automatically cleans your Desktop by moving all screenshots to a new folder; and (2) writing a blog post about said script.

I began the project by looking at my actual Desktop and thinking about how to tailor the stated task to meet my actual needs. A minimally acceptable solution is to create a new folder and transfer all .png images into it, but that would hardly make a dent in the 99 items contained in C:\Users\MyName\Desktop. Therefore, my revised plan is to automatically move:

.pngs, .svgs, and .gifs into a new subdirectory, PICS;
.txts, .mds, and .rtfs into NOTES;
.pdfs into PDFS; and
.c source files into CODE.

Yes, I have outed myself. I am a C developer. You won't find a lick of Python on my cluttered Desktop, yet.

Setting the Path to my Desktop

If I were coding this tool at work, the path to the Desktop would likely be set via a command line argument. However, we haven't "officially" learned to parse command line arguments with sys.argv() or argparse yet. Another option would be to prompt for user input, but during a lab exercise, I had a bad experience where I meant to type C:\Users\MyName\Desktop\TestFolder, but I missed the \ key and hit Enter early, mistakenly running faulty work-in-progress code against my actual Desktop! (Fortunately, that script crashed after moving a single file to where I didn't want it). In the interest of safety, I will hardcode the path thus:

desktop = pathlib.Path(r"C:\Users\MyName\Desktop\TestFolder")

Only after I've tested the script against TestDir will I shorten the path to run things against my Desktop for real.

Giving credit where credit is due, Stack Overflow straightened me out when my initial code was wrong. The Windows path separator \ easily collides with Unicode escape sequences, so I added r to create a raw string, slightly easier than escaping each path separator.

Creating the New Directories

Since I want to create a series of new directories, not just one, I iterated through a list of names, joining them to the desktop path.

for sub_dir in ["CODE", "NOTES", "PDFS", "PICS"]:
    new_dir = desktop.joinpath(sub_dir)
    new_dir.mkdir(exist_ok=True)

The exist_ok argument should make testing less tedious, since the script won't error out if run in succession without deleting the new folders in between.

Identifying and Relocating Files

A hefty for loop did all the heavy lifting.

# Filter for screenshots only
for each in desktop.iterdir():
    if not each.is_file():
        # Skip directories
        continue

    extension = each.suffix.lower()

    # Create a new path for each file
    if extension in [".c", ".h", ".py"]:
        # put it in CODE
        new_path = desktop / "CODE" / each.name

    elif extension in [".md", ".rtf", ".txt"]:
        # put it in NOTES
        new_path = desktop / "NOTES" / each.name

    elif extension == ".pdf":
        # put it in PDFS
        new_path = desktop / "PDFS" / each.name

    elif extension in [".bmp", ".gif", ".jpg", ".jpeg", ".svg", ".png"]:
        # put it in PICS
        new_path = desktop / "PICS" / each.name

    else:
        continue

First, I iterated through every file on the Desktop using iterdir(). Second, to recognize file types in a case-insensitive fashion, I converted the suffix of each file to lowercase and tested whether it was found in a list of file extensions belonging to the same category. Third, I set a new_path variable with the future location of the file. As a convenience, pathlib.Path supports building paths using the / operator; I find that more readable than the joinpath() method when you have multiple pieces to string together.

files_moved = 0

....

# Move the screenshot there
print(f"[!] Moving {each} to {new_path}...")
each.rename(new_path)
files_moved += 1

Finally, each file from the for loop was moved to new_path using the rename() method. For my own edification, I added a files_moved variable to quantify the work completed by the automation script.

Running it...

When I changed the path from the test directory to my actual Desktop, the script proudly reported [+] Successfully moved 41 files!. This was nice and all, but a quick visual inspection told me that the PDFs stayed put. Notice that unlike the other categories of files, there is only one valid file extension for a PDF. The initial version of my code had a silly logic bug that was syntactically valid: elif extension == [".pdf"]:. After quickly fixing that and re-running the script, 16 additional files were relocated.

Now, with my Desktop in a semblance of order, I can tackle individual subdirectories at my leisure and delete any files that do not spark joy.

Complete Code Listing

# Write a script that moves all files with the .png extension
# from one folder to another
""" Clean up my Desktop Automagically """

import pathlib

# Find the path to my Desktop
desktop = pathlib.Path(r"C:\Users\MyName\Desktop")

# Create a new folder
for sub_dir in ["CODE", "NOTES", "PDFS", "PICS"]:
    new_dir = desktop.joinpath(sub_dir)
    new_dir.mkdir(exist_ok=True)

files_moved = 0

# Filter for screenshots only
for each in desktop.iterdir():
    if not each.is_file():
        # Skip directories
        continue

    extension = each.suffix.lower()

    # Create a new path for each file
    if extension in [".c", ".h", ".py"]:
        # put it in CODE
        new_path = desktop / "CODE" / each.name

    elif extension in [".md", ".rtf", ".txt"]:
        # put it in NOTES
        new_path = desktop / "NOTES" / each.name

    elif extension == ".pdf":
        # put it in PDFS
        new_path = desktop / "PDFS" / each.name

    elif extension in [".bmp", ".gif", ".jpg", ".jpeg", ".svg", ".png"]:
        # put it in PICS
        new_path = desktop / "PICS" / each.name

    else:
        continue

    # Move the screenshot there
    print(f"[!] Moving {each} to {new_path}...")
    each.rename(new_path)
    files_moved += 1

if files_moved > 0:
    print(f"[+] Successfully moved {files_moved} files!")

Writing Hangman with Coding Nomads

Milnor — Mon, 15 May 2023 21:27:24 +0000

Intro

Recently I started the Python Bootcamp offered by Coding Nomads, despite being a professional developer already. I originally learned Python in a haphazard manner: Googling "how to X in python", then pasting together useful snippets from Stack Overflow. Now it's back to the basics as I re-learn how to use the language in a more idiomatic fashion under the guidance of a mentor. A complete code listing of my Hangman implementation is pasted at the bottom, but first I'll comment on design decisions, challenges, etc. in select snippets.

I grew up playing "Hangman" using paper-and-pencil. If the rules are unfamiliar to you, try the game's Wikipedia page. In a nutshell, you have a finite number of guesses to come up with all the letters in a mystery word. With each correct guess, you are shown all occurrences of a letter within the word. With each wrong guess, body parts are added to a simple sketch of you hanging from a noose.

Displaying the Word

Initially, I was tracking a secret_word string variable along with two lists (right_letters and wrong_letters) guessed by the player. At first I just printed the word (including only the correctly guessed letters) to the screen; e.g. _ e _ _ _. Later I decided to save this representation of the word to a variable word_in_progress, since winning the game could be detected when the string no longer contained any underscores.

secret_word = "crumpet"

right_letters = []
wrong_letters = []

    # Display the word as a sequence of blanks, e.g. "_ _ _ _ _" for "hello"
    # When they find a correct character, display the blank with the word
    #   filled in, e.g.: "_ e _ _ _" if they guessed "e" from "hello"
    word_in_progress = ""
    for each in secret_word:
        if each in right_letters:
            word_in_progress += each + " "
        else:
            word_in_progress += "_ "
    print(word_in_progress)

Embellishment: Adding ASCII Art

What CLI game would be complete without ASCII art graphics?
I created a multi-line string variable wrong_6 to represent losing the game and being hanged by the neck until dead. Then I worked backwards with wrong_5 (one leg missing) through wrong_0 (an empty gallows).

wrong_6 = """
========
 ||  |
 ||  O
 || /|\
 || / \
 ||
===========
"""

When I ran the game; however, something looked off. I soon remembered that \ is often an escape character in programming languages, so I corrected the limbs on the right side of the drawing to look like this:

wrong_6 = """
========
 ||  |
 ||  O
 || /|\\
 || / \\
 ||
===========
"""

Linting Headaches

New programmers may be unfamiliar with the term linting. It refers to running your code through a static analysis tool (called a linter) that warns you when you don't conform to best practices for the language you are writing. In the case of Python, for instance, PEP-8 is the authoritative standard on best practices and pylint one of the popular linters. Black is also a great linter that should be on your radar, though I don't discuss it further here.

At my job as a developer, if I write code that doesn't pass pylint (or another language-specific linter, as appropriate), my commit will get rejected.

Naming Conventions

I ran python -m pylint hangman.py and received several warnings about naming conventions. (Note: If you are a Linux developer, assuming pylint is already installed, you should be able to run it more simply: pylint hangman.py).

hangman.py:68:0: C0103: Constant name "wrong_4" doesn't conform to UPPER_CASE naming style (invalid-name)
hangman.py:78:0: C0103: Constant name "wrong_5" doesn't conform to UPPER_CASE naming style (invalid-name)
hangman.py:88:0: C0103: Constant name "wrong_6" doesn't conform to UPPER_CASE naming style (invalid-name)
hangman.py:109:4: C0103: Constant name "word_in_progress" doesn't conform to UPPER_CASE naming style (invalid-name)
hangman.py:155:8: C0103: Constant name "your_letter" doesn't conform to UPPER_CASE naming style (invalid-name)
hangman.py:160:16: C0103: Constant name "your_letter" doesn't conform to UPPER_CASE naming style (invalid-name)

Since I am primarily a C developer and learning to write Python like an adult is relatively new, these warnings suggest to me: "I, your great and mighty linter, believe that your global variables are all constants, kind of like a #define PI 3.14 in C, and ought to be written in ALL_CAPS rather than snake_case." However, since I'm still early on in the Coding Nomads bootcamp and don't know the best practices, I decided to kick the can down the road.

Instead of refactoring to avoid global variables or painstakingly rename them all, a quick Google search told me that I could disable the warning with # pylint: disable=invalid-name. 😎

Long Lines

There was another linting error that I decided did need fixing. One line of the code was very long:

if your_letter in right_letters or your_letter in wrong_letters or not your_letter.isalpha():

I didn't trust the user to guess a letter that hadn't already been guessed. In fact, I don't trust the user to even guess a "letter" that is even alphanumeric, let alone alphabetic. So, I wrapped the user input in a while loop that continues ad infinitum until they get it right. (Note: If you are a new developer and haven't learned to sanitize your inputs, you really ought to read the Bobby Tables cartoon by XKCD.)

Pardon the rabbit trail about why that long line was necessary. The question was how to shorten it so that pylint would accept my code. Python is very sensitive to whitespace being just so, so when I split the long line into two, it complained about how I did it.

            if your_letter in right_letters or your_letter in wrong_letters or not
            your_letter.isalpha():

hangman.py:158:83: E0001: Parsing failed: 'invalid syntax (<unknown>, line 158)' (syntax-error)

A little more Googling combined with trial-and-error determined that this would work:

            if your_letter in right_letters or your_letter in wrong_letters or not \
               your_letter.isalpha():

Randomizing the Secret Word (Potential Spoiler)

The course suggested this optional extension to make the game more interesting: "If you want to practice your online research skills, then explore some possible ways to get a word into your game that you don't know yourself. That would make it a lot more fun to play the game by yourself."

Initially, to test the script during development, I hard-coded an arbitrary "secret" word to guess:

# Hard-code a word that needs to be guessed in the script
secret_word = "crumpet"

Where could I go to get a large pool of words? If I were working in a Linux environment, there would likely be an entire dictionary available within /usr/share/dict/. Alas, my Linux VM (virtual machine) was freezing for unknown reasons, so I began this project in the terra incognita of a Windows 11 environment.

Our good friend Google led me to a question on Stack Overflow about writing a random word generator in Python. The accepted answer was written for Python2, but just below it was a Python3 alternative using urllib from the standard library. It pointed to a website that was down at the time I tried it -- though as of writing this blog post, it has come back up -- so I swapped in the URL from the Python2 example and everything worked beautifully.

import random
import urllib.request

word_url = "https://www.mit.edu/~ecprice/wordlist.10000"
response = urllib.request.urlopen(word_url)
long_txt = response.read().decode()
words = long_txt.splitlines()
secret_word = random.choice(words)

Code Listing

The complete code differs slightly from the snippets above due to changes under version control (the original sits within a private repo on GitHub) as well as pulling out just the parts relevant to a topic of discussion.

""" The Game of Hangman """
# pylint: disable=invalid-name

import random
import sys
import urllib.request

# adapted from https://stackoverflow.com/questions/18834636/random-word-generator-python
word_url = "https://www.mit.edu/~ecprice/wordlist.10000"
response = urllib.request.urlopen(word_url)
long_txt = response.read().decode()
words = long_txt.splitlines()
secret_word = random.choice(words)

right_letters = []
wrong_letters = []

# Create a counter for how many tries a user has
wrong = 0   # number of incorrect guesses, up to 6

wrong_0 = """
========
 ||  |
 ||  
 || 
 || 
 ||
===========
"""

wrong_1 = """
========
 ||  |
 ||  O
 || 
 || 
 ||
===========
"""

wrong_2 = """
========
 ||  |
 ||  O
 ||  |
 || 
 ||
===========
"""

wrong_3 = """
========
 ||  |
 ||  O
 || /|
 || 
 ||
===========
"""

wrong_4 = """
========
 ||  |
 ||  O
 || /|\\
 || 
 ||
===========
"""

wrong_5 = """
========
 ||  |
 ||  O
 || /|\\
 ||   \\
 ||
===========
"""

wrong_6 = """
========
 ||  |
 ||  O
 || /|\\
 || / \\
 ||
===========
"""

# Print an explanation to the user
print("  =======================")
print(" / Welcome to Hangman! /")
print("======================= ")

# Keep asking them for their guess until they won or lost
while wrong <= 6:
    # Display the word as a sequence of blanks, e.g. "_ _ _ _ _" for "hello"
    # When they find a correct character, display the blank with the word
    #   filled in, e.g.: "_ e _ _ _" if they guessed "e" from "hello"
    word_in_progress = ""
    for each in secret_word:
        if each in right_letters:
            word_in_progress += each + " "
        else:
            word_in_progress += "_ "
    print(word_in_progress)

    # My embellishments
    if wrong == 0:
        print(wrong_0)
    elif wrong == 1:
        print(wrong_2)
    elif wrong == 2:
        print(wrong_1)
    elif wrong == 3:
        print(wrong_3)
    elif wrong == 4:
        print(wrong_4)
    elif wrong == 5:
        print(wrong_5)
    elif wrong == 6:
        print(wrong_6)

    print("Correct Guesses: ", end=' ')
    for each in right_letters:
        print(each, end=' ')
    print("")

    print("Incorrect Guesses: ", end=' ')
    for each in wrong_letters:
        print(each, end=' ')
    print("")

    # Ask for user input
    if wrong == 6:
        # Display a losing message and quit the game if they don't make it
        print("Sorry, you lose.")
        sys.exit()
    elif "_" not in word_in_progress:
        # Display a winning message and the full word if they win
        print("Congrats, you win.")
        sys.exit()
    else:
        # Allow only single-character alphabetic input
        print("\n\n")
        your_letter = None
        while your_letter is None:
            your_letter = input("Guess a letter: ").lower()
            if your_letter in right_letters or your_letter in wrong_letters or not \
               your_letter.isalpha():
                your_letter = None
                continue
            if your_letter in secret_word:
                print("Good guess!")
                right_letters.append(your_letter)
            else:
                print("Nope!")
                wrong_letters.append(your_letter)
                wrong += 1

About Me

I get paid to code, but also put much effort into drawing silly cover art in MS Paint to adorn software user manuals and the occasional blog post.