Python

File

• Open modes:

  

• Open modes decision tree:

  

Class & Function

• Get full path:

  import os
  import inspect
  
  def foo():
    pass
  
  print(os.path.abspath(inspect.getfile(foo)))
  
  class Bar:
    pass
  
  print(os.path.abspath(inspect.getfile(Bar.__class__)))
  

Modules & Packages

• Get all import able modules & packages:

  import pkgutil
  search_path = ['.'] # set to None to see all modules importable from sys.path
  all_modules = [x[1] for x in pkgutil.iter_modules(path=search_path)]
  print(all_modules)
  

Celery

• Kill celery process:

  kill -9 $(ps aux | grep celery | grep -v grep | awk '{print $2}' | tr '\n' ' ') > /dev/null 2>&1
  

• View worker logs:

  celery -A <worker name: karestoon> worker --loglevel=info
  

PIP

• Install from source (Unix path):

  pip install file:///path/to/package
  

Operators

• Overview

  

• The "i" symbol means "in place"

• The "a" symbol means "asynchronous"
• The "r" symbol means "reverse"
• When we are implementing the "Rich comparison" method we should return a new object, in the other hand for the "Augmented assignment arithmetic" method we should update the current object

Other

• Growth rates of common functions measured in nanoseconds:

  n	lg n	n	n lg n	n²	2ⁿ	n!
  10	0.003 μs	0.01 μs	0.033 μs	0.1 μs	1 μs	3.63 ms
  20	0.004 μs	0.02 μs	0.086 μs	0.4 μs	1 ms	77.1 years
  30	0.005 μs	0.03 μs	0.147 μs	0.9 μs	1 sec	8.4 × 10¹⁵ yrs
  40	0.005 μs	0.04 μs	0.213 μs	1.6 μs	18.3 min
  50	0.006 μs	0.05 μs	0.282 μs	2.5 μs	13 days
  100	0.007 μs	0.1 μs	0.644 μs	10 μs	4 × 10¹³ yrs
  1,000	0.010 μs	1.00 μs	9.966 μs	1 ms
  10,000	0.013 μs	10 μs	130 μs	100 ms
  100,000	0.017 μs	0.10 ms	1.67 ms	10 sec
  1,000,000	0.020 μs	1 ms	19.93 ms	16.7 min
  10,000,000	0.023 μs	0.01 sec	0.23 sec	1.16 days
  100,000,000	0.027 μs	0.10 sec	2.66 sec	115.7 days
  1,000,000,000	0.030 μs	1 sec	29.90 sec	31.7 years

• cProfile example: