An extemely short introduction to Python

python_intro.md

An extemely short introduction to Python

• General information
  • High-level scripting language
  • Dynamic and strong typing
  • Implemented in C (as is NumPy/SciPy)
  • Extremely widespread: Google (YouTube, Google Brain, DeepMind), Dropbox, Microsoft, Intel are the largest supporters
  • Clear, simple syntax
  • Mostly object-oriented, but has a lot of functional influence
  • Named after Monty Python, not the animal!
  • First released in 1991
  • Often compared with Ruby or Perl; in contrast to Ruby...
  • Works on different platforms: Windows, Linux, mac OS, x86, ARM, microcontrollers, ...
• Applications
  • Literally everything and everywhere
• Tooling:
  • python (useful: the -i flag)
  • ipython (useful: who and whos, ?)
  • Jupyter Notebook
  • PyCharm (also Community Edition)
  • Spyder
  • pip and conda
• Python 3 vs Python 2:
  • UTF-8 as default source file encoding
  • Syntax: print function
  • Semantics: Laziness, integer division
  • Unicode strings by default + separate bytes and bytearray classes
  • python vs python3 on Linux
• Libraries:
  • NumPy
  • SciPy
  • SymPy
  • matplotlib
  • python-control
  • scikit-learn, scikit-image, astropy, ...
  • Keras, TensorFlow, Theano
  • Numba
• Finding information:
  • Be careful about the docs version (e.g. use the latest NumPy/SciPy docs, Python 3.6 etc.)
  • Use Zeal or Dash
  • Use StackOverflow (just google in English)
  • There always is a solution for your problem!
  • Read docstrings / use help() or ?
  • NumPy/SciPy: If in doubt, read the source
• Best practices:
  • Zen of Python (PEP 20)
  • PEP 8
  • Hard tabs vs spaces: Use 4 spaces, full stop
  • Flat source code: Use list/set/dict comprehensions and generators
• Python basics
  • Syntax:
    • definition of variables and functions, default, named and positional args
    • import statements
    • indexing and slicing
    • branches
    • loops
    • IO (print)
    • strings and string interpolation
  • Operators and statements:
    • not
    • @
    • **
    • _ when unpacking
    • None as a nil value
    • pass
  • Data structures:
    • tuples, tuples unpacking
    • lists
    • dicts
    • sets
    • ndarrays
  • Misc:
    • list comprehensions
    • iteration, enumerate, zip
    • functions are first-order citizens
    • laziness: e.g. map, list
  • Naming conventions
    • snake_case and SCREAMING_SNAKE_CASE
    • Underscores magic _
  • Special symbols:
    • __version__
    • __init__()
    • __name__
  • Classes and objects: a completely different story
  • Pitfalls:
    • mutable objects as default args
    • closures capture references (late binding)