19_standard_library_test1.py

# Demonstrates how to use some modules from the std library.
import os
import shutil
import glob
import zlib
import zipfile
import sys
import urllib.request
import json
import datetime
import timeit
import time
import doctest

# Demonstrates timing this file module using 2 different methods.
start_dt = datetime.datetime.now()
start_s = time.time()

# Current working directory.
print(os.getcwd())
# Change working directory.
# To go back up, use os.chdir('..').
# There is a small difference between / and \ when writing file paths.
# Unix systems only accept /. Windows accepts / and \, but if both are mixed
# together, it only accepts \. Changing / to \ can fix windows based errors
# in some codes.
os.chdir(os.getcwd() + r'\files')
# Lists all files and folders in a directory.
print(os.listdir(os.getcwd()))
# Makes and removes a directory. Path can also be used instead.
# os.makedirs does the same thing but also creates all intemediate dirs
# if you give it a path.
os.mkdir('testdir')
os.rmdir('testdir')
# A common command that joins the directory path to the filename.
file_path = os.path.abspath(os.path.join(os.getcwd(), 'test.txt'))
print(file_path)
# Returns the filename again.
print(os.path.basename(file_path))
# Runs commands in cmd. In this case returns working directory.
# Other commands include mkdir (make directory) and rmdir.
print(os.system('echo %cd%'))
print()

# Checks if file exists.
if os.path.exists(file_path):
    os.system('del test.txt')
# Making text file.
os.system('echo testing > test.txt')
os.system('del test.txt')
# dir and help are common general commands.
# The first lists all possible commands,
# the second retrieves help documentation.
# print(dir(os))
# print(help(os))

# Suggested module for file and directory management.
shutil.copyfile('file.txt', 'test.txt')
# Does the same as above but you can use path as a target instead of filename.
# If a dir is specified as target path, the file will have the same name as
# the original.
# shutil.copy('file.txt',
#             os.path.join(os.getcwd(), 'test.txt'))

# Makes file lists from wildcard searches.
# Most often used for file types, such as './dir/*.filetype' but also has
# subdirectory functionality in python 3.5+ using './dir/**/*.filetype'
# If wildcard searches are not required, use os.listdir(path) instead.
# Note that glob returns files with their full path, while os.listdir lists
# directory and filenames only.
# Demonstrated here with data compression.
print(glob.glob('*.txt'))
# You need rb here to perform compression.
for file in glob.glob('*.txt'):
    with open(file, 'rb') as f:
        original_data = f.read()
        compressed_data = zlib.compress(original_data, zlib.Z_BEST_COMPRESSION)
        compress_ratio = (float(len(original_data)) -
                          float(len(compressed_data))) / float(len(original_data))
        print('{}: {} => {} or {:.2%} compression'.format(
            file, len(original_data), len(compressed_data), compress_ratio))
print()

# Dealing with zipfiles.
filename = 'zipfile.zip'
# Writing a zipfile.
with zipfile.ZipFile(filename, 'w') as zip:
    for file in glob.glob('*.txt'):
        zip.write(file)

with zipfile.ZipFile(filename, 'r') as zip:
    # Lists contents of zipfile.
    zip.printdir()
    # Extracts to target dir. Defaults to working dir if target not specified.
    zip.extractall(os.getcwd() + r'\zipdir')
print()

# sys.argv is used to determine if the script is called in cmd with the
# correct marameters. sys.arg[0] always contains the script name if
# cmd is not run.
print(sys.argv)
print()
# Usage of sys.argv will be demonstrated in mymodule1.py

# urllib is basically a worse version of requests module.
url = 'https://raw.githubusercontent.com/persocom01/TestPython/master/files/file3.txt'
result = json.load(urllib.request.urlopen(url))
print(result)
print()

# Datetime manipulation.
today = datetime.date.today()
print('today: ' + str(today))
now = datetime.datetime.now()
print('now: ' + str(now))
# Gets the UNIX timestamp.
timestamp = datetime.datetime.timestamp(now)
print('timestamp: ' + str(timestamp))
print(now.year)
print(now.month)
print(now.day)
# Format code list.
# %a	Abbreviated weekday name.	Sun, Mon, ...
# %A	Full weekday name.	Sunday, Monday, ...
# %w	Weekday as a decimal number.	0, 1, ..., 6
# %d	Day of the month as a zero-padded decimal.	01, 02, ..., 31
# %-d	Day of the month as a decimal number.	1, 2, ..., 30
# %b	Abbreviated month name.	Jan, Feb, ..., Dec
# %B	Full month name.	January, February, ...
# %m	Month as a zero-padded decimal number.	01, 02, ..., 12
# %-m	Month as a decimal number.	1, 2, ..., 12
# %y	Year without century as a zero-padded decimal number.	00, 01, ..., 99
# %-y	Year without century as a decimal number.	0, 1, ..., 99
# %Y	Year with century as a decimal number.	2013, 2019 etc.
# %H	Hour (24-hour clock) as a zero-padded decimal number.	00, 01, ..., 23
# %-H	Hour (24-hour clock) as a decimal number.	0, 1, ..., 23
# %I	Hour (12-hour clock) as a zero-padded decimal number.	01, 02, ..., 12
# %-I	Hour (12-hour clock) as a decimal number.	1, 2, ... 12
# %p	Locale’s AM or PM.	AM, PM
# %M	Minute as a zero-padded decimal number.	00, 01, ..., 59
# %-M	Minute as a decimal number.	0, 1, ..., 59
# %S	Second as a zero-padded decimal number.	00, 01, ..., 59
# %-S	Second as a decimal number.	0, 1, ..., 59
# %f	Microsecond as a decimal number, zero-padded on the left.	000000 - 999999
# %z	UTC offset in the form +HHMM or -HHMM.
# %Z	Time zone name.
# %j	Day of the year as a zero-padded decimal number.	001, 002, ..., 366
# %-j	Day of the year as a decimal number.	1, 2, ..., 366
# %U	Week number of the year (Sunday as the first day of the week). All days in a new year preceding the first Sunday are considered to be in week 0.	00, 01, ..., 53
# %W	Week number of the year (Monday as the first day of the week). All days in a new year preceding the first Monday are considered to be in week 0.	00, 01, ..., 53
# %c	Locale’s appropriate date and time representation.	Mon Sep 30 07:06:05 2013
# %x	Locale’s appropriate date representation.	09/30/13
# %X	Locale’s appropriate time representation.	07:06:05
# %%	A literal '%' character.	%
format = '%m-%d-%y. %d %b %Y is a %A on the %d day of %B.'
print(now.strftime(format))
# Use date.timedelta() to manipulate datetime objects.
yesterday = datetime.date.today() - datetime.timedelta(days=1)
format = 'yesterday\'s date was %Y-%m-%d'
print(yesterday.strftime(format))
# Calendar math YYYY, M, D format.
y2k = datetime.datetime(1999, 12, 31)
time_since = now - y2k
print(f'no of days since {y2k}: ' + str(time_since.days))
print()

# Timing processes.
zip_process = timeit.Timer(
    stmt='zlib.compress(data, zlib.Z_BEST_COMPRESSION)',
    setup='import zlib; data=open(\'file3.txt\', \'rb\').read()',
)
time_taken_in_microseconds = zip_process.timeit(1) * 10**6
print('Time taken for 1 interation(s) =',
      time_taken_in_microseconds, 'microseconds')
# It is also possible to time simple statements.
print(timeit.timeit('10**6', number=1000000))
print()

# doctest scans for and validates modules.
# It allows you to put module tests in ''' comments '''.
# The tests must be written in the below specific way,
# with >>> module(input) indicating the module run with the result below.
# Error results are written in the below specific way.


def celcius_to_kelvin(x):
    '''
    >>> celcius_to_kelvin(1)
    274.15
    >>> celcius_to_kelvin(-500)
    Traceback (most recent call last):
        ...
    ValueError: Temperature cannot be below -273.15 degrees Celcius.
    '''

    if x < -273.15:
        raise ValueError(
            'Temperature cannot be below -273.15 degrees Celcius.')
    else:
        return x + 273.15


print(celcius_to_kelvin(1))
print(doctest.testmod())
print()

end_dt = datetime.datetime.now()
end_s = time.time()
total_dt = end_dt - start_dt
total_s = end_s - start_s
print(f'module time using datetime: {total_dt}')
print(f'module time using time: {total_s}')