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Useful Python Libraries

A list of useful Python libraries

Credit: https://github.com/judy2k/command-line-talk

Command Line Parsing Libraries

  • Built-in
    • getopt
    • optparse
    • argparse
  • 3rd Party
    • docopt
    • click
    • clint
    • compago

Input Output

Logging

logging.basicConfig(level=logging.WARNING, format="%(msg)s")

if options.verbose: logging.getLogger().setLevel(logging.DEBUG)

LOG = logging.getLogger('logtest') 

LOG.debug('Running main')
LOG.info('Everything is okay')
LOG.warning('EVERYTHING HAS GONE WRONG!')

Terminal Input or Piped Input?

Sample code:

from sys import stdin, stdout, stderr

print "Piped input:", not stdin.isatty()
print "Piped output:", not stdout.isatty()
print "Piped error:", not stderr.isatty()

Output:

$ ./isatty.py 

Piped input: False
Piped output: False
Piped error: False  

$ ./isatty.py | cat 

Piped input: False
Piped output: True
Piped error: False 

$ echo 'Hello' | ./isatty.py | cat 

Piped input: True
Piped output: True
Piped error: False

Color

Library: Colorama PyPi Documentation: https://pypi.org/project/colorama/

from colorama import Fore, Back, Style  

print Fore.RED + 'some red text'  
print Back.GREEN + 'and with a green background' print Style.BRIGHT + 'and in bright text',
print Fore.RESET + Back.RESET + Style.RESET_ALL print 'back to normal now'

Problem with this: When captured in a log file, color-related characters are also seen.

$ ./colour > saved_data.txt
  
$ vim saved_data.txt  
^[[31msome red text

^[[42mand with a green background ^[[1mand in bright text ^[[39m^[[49m^[[0m back to normal now

Solution:

Set strip=True

import colorama

if not sys.stdout.isatty():
    colorama.init(strip=True)

print Fore.RED + 'some red text'  
print Back.GREEN + ‘and a green background'

User Credentials

import getpass 

username = getpass.getuser()  
password = getpass.getpass()  
  
print ( “You are {username}, and you should never use the password ‘{password}’ again!”.format(
username=username,
password=password
)

Here, getpass.getuser() can get the current user from the system.

Progress

Library: progressbar2

PyPi Documentation: https://pypi.org/project/progressbar2/

Sample Code:

from progressbar import * import time  
  
progress = ProgressBar()  
for i in progress(range(80)):
	time.sleep(0.01)

Output:

# 100% |#######################################|

Widgets:

Sample Code:

widgets = ['Loading: ', Percentage(), ' ', Bar(),
           ' ', ETA(), ' ', FileTransferSpeed()] 

pbar = ProgressBar(widgets=widgets, maxval=20000).start() 

for i in range(20000): pbar.update(i)
 time.sleep(.005)
pbar.finish()

Output:

# Loading:   9% |#                                      | ETA:  0:01:42 177.08  B/s

Configuration

  • Built-in:
    • ini
    • Environment Variables
    • json
    • csv
    • xml
    • Apple plist
  • 3rd Party:
    • yaml
    • Java Properties

ini Files

from ConfigParser import SafeConfigParser from os.path import dirname, join, expanduser
  
INSTALL_DIR = dirname(__file__)  
  
config = SafeConfigParser()  
config.read([
	join(INSTALL_DIR, 'defaults.ini'), expanduser(‘~/.tool.ini’), 'config.ini'
])

Examples:

print config.get('server', ‘host’)
=> www.ninjarockstar.guru

print config.getint('server', ‘port')
=> 5000

print config.get('server', ‘url’)
=> http://www.ninjarockstar.guru:5000/

Signals

import signal  

signal.siginterrupt(signal.SIGINFO, False)  

signal.signal(signal.SIGINFO, mysiginfofunc)

KeyboardInterrupt:

def main():
	try:
		time.sleep(5)
	except KeyboardInterrupt:
		pass

if __name__ == '__main__':
	main()

Code Structure & Packaging

Structure:

mytool-project/
  setup.py
  mytool
  mytoollib/ 
 __init__.py
   __main__.py 
 mytool.py
   utils.py

setuptools:

# setup.py
setup(name = 'mytool',
    version = '2.0',
    url = ‘http://mytool.ninjarockstar.guru/',
    license = 'BSD License',
    author = ‘Mark Smith',
    author_email = ‘judy@judy.co.uk’,
    description = ‘A tool with little purpose.',
    keywords = 'utils',
    packages = ‘mytoollib’,
    scripts = [‘mytool’]
    platforms = ‘any')

Exit Codes

# Normal termination exits with 0
# Uncaught exceptions exit with 1
# ... or you can explicitly exit: sys.exit(exit_code)