Brief Tour of the Standard Library I

Notes on Chapter 10 of the Python Tutorial (3.7.5), Brief Tour of the Standard Library, Part I.

I’ve already used the following modules from the standard library by completing through half of Chapter 16 of Automate the Boring Stuff with Python:

• copy
• csv
• datetime
• json
• logging
• math
• os
• pprint
• random
• re
• shelve
• shutil
• smtplib
• sys
• threading
• time
• traceback
• webbrowser
• zipfile

That’s nineteen modules so far - and I might have used a few more when working through other tutorials, etc.

By going through this section, I’m looking forward to:

1. Learn about modules I haven’t encountered yet
2. Learn more about modules I have used before, and
3. Learn more about the history, structure and future prospects for the standard library

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New (to me) modules:

argparse

• argparse provides more sophisticated ways tow work with command line arguments than sys.argv

doctest

• This module can scan another module and validate the tests embedded in a program’s doctstring
• To work, there need to be three angle brackets in front of the call. (e.g. >>> print(average(\[20, 30, 50])

glob

• glob.glob(*pathname*) returns a list of all pathnames in the current working directory that match the specified pattern.

statistics

• This module calculates various basic statistical properties (e.g. mean, median, variance) of a given list of numeric data

timeit

• Used for performance measurement

unittest

• Includes a more comprehensive set of tests than doctest

urllib.request

• The requests module provides the same functionality as this module, I think, but is easier to use

zlib

• Module for data compression.
• zlib.compress(*data, level*) takes a byte-like object for the data, not a string. To make a bytes-like object from a string, put a ‘b’ in front of the string. (e.g. s = b'This will produce a bytes-like object')

Modules I’d used before:

os

• This is one of the modules I’ve been using most frequently, especially os.getcwd() and os.chdir()
• Before today I haven’t known how to specify the new desired path in os.chdir() using a relative path. Today I learned how to do this. os.chdir(*'./folder-name'*) changes the current working directory (CWD) to the specified folder within the current directory. os.chdir(*'../folder-name'*) changes the CWD to the specified folder within the parent folder of the current directory.
• I clarified that for relative paths there are only dot (.) and dot-dot (..) folders. I had thought that there could be an arbitary number of dots - e.g. dot-dot-dot (…) - but this is not true, at least from what I see looking back at ABS.
• os.system(command) - Executes the command (which is a string) in a subshell. This is still unclear to me. What’s a subshell?
• Reminded to use dir(*module-name*) to get a directory of all functions in a module, and help(*module-name*)to get a manual page from the module’s docstring.

random

• The function random.choice(*[list]*) chooses a random value from the given list.

re

• String methods are preferred to re for simple tasks because they are easier to read and debug

shutil

• For daily file & directory management, shutil is easier to use than os

sys

• The most direct way to terminate a script is sys.exit()

History, structure & future prospects of the Python standard library:

• The tutorial didn’t address this explictly. I’ll look to learn about this as I read more & go to events, talk to people, etc.