Beginner’s Python¶
The GeoWATCH software is primarilly implemented in Python. To understand the codebase it will help to be familiar with Python basics. This document provides a list of commonly used concepts and links to documentation.
Python datastructures like lists, sets, and dictionaries: https://docs.python.org/3/tutorial/datastructures.html and the time complexity of their associated operations: https://wiki.python.org/moin/TimeComplexity
Parameter unpacking with *args and **kwargs: https://stackoverflow.com/questions/36901/what-does-double-star-asterisk-and-star-asterisk-do-for-parameters
List comprehensions
An understanding of the terms:
* expression
* assignment
* function
* property
* attribute
* dunder
* comprehension
* generator
* iterator
* callable
* iterable
* dictionary
* list
* module
* class
* method
* instance
* type
* namespace
Python Keywords¶
Official docs are here: https://docs.python.org/3/reference/lexical_analysis.html#keywords It is imporant to be familiar with most of Python’s keywords.
The majority of Python keywords are commonly used. It is imporatnt to understand
# Values
False None True
# Definitions
class def
# Errors
try except finally raise
# Conditions
if elif else
# Contextual
with
# Imports
import from as
# Operators
in is not or and
# Loops
for while continue break
# Imperative
assert return yield
Less common keywords that you should be aware of:
# Async
async await
# Definitions
lambda
# Scoping
nonlocal global
# Imperative
del pass
Dunder Methods¶
Duner refers to names that start with two (double) underscores: e.g. In
conversation it is easier to say “duner init” instead of __init__.
Duner methods are part of Python’s data model, which has many features: https://docs.python.org/3/reference/datamodel.html but a subset of those are commonly used and you should be familar with the following dunder methods you can overload on a class:
* __init__
* __str__, * __repr__
* __len__
* __dir__
* __call__
* __iter__
* __contains__
* __getitem__, __setitem__
* __getattr__, __setattr__
* __add__, __sub__, __mul__, __truediv__
* __and__, __or__, __xor__
* __enter__, __exit__
You should also be aware of duner attributes like:
* __dict__
* __class__
* __name__
* __file__
* __path__
Standard Library Modules¶
Knowledge of the special duner methods:
The stdlib modules:
argparse, itertools, functools, datetime, copy, collections, math, decimal,
fractions, importlib, json, pathlib, pickle, platform, stat, re, random,
shutil, textwrap, warnings
Pypi Modules¶
Third party modules:
numpy, scipy, torch, pandas, ubelt, xdoctest
matplotlib, seaborn,
shapely, rich, networkx,
pytorch_lightning
Builtins¶
# Debug
breakpoint,
# Async
aiter,
anext,
# Bytes
bytearray,
bytes,
# Strings
format,
hash,
ascii,
bin, hex, oct, ord,
chr,
str, repr,
# Interpreter
compile, eval, exec,
# Introspection
type,
dir,
isinstance, issubclass,
callable,
vars, globals, locals,
id,
len,
# Attributes
delattr, getattr, hasattr, setattr,
# Math
abs, sum, pow,
divmod, round,
max, min,
sorted,
all, any,
# Constants
False, True, None,
Ellipsis,
NotImplemented,
# Low Level
memoryview,
# Numeric Structures
bool,
int,
complex,
float,
# IO Functions
input,
print,
open,
# Data Structures
tuple,
dict,
set,
list,
frozenset,
# Iterators
iter,
reversed,
range,
enumerate,
filter,
map,
zip,
next,
# Object Oriented
property,
object,
super,
staticmethod,
classmethod,
# Imperative
slice,
# Common Exceptions
Exception,
KeyboardInterrupt,
AssertionError,
AttributeError,
MemoryError,
ImportError,
NameError,
TypeError,
ValueError,
IndexError,
IOError,
KeyError,
NotImplementedError,
# Uncommon Exceptions
BaseException, BaseExceptionGroup, GeneratorExit, SystemExit, ArithmeticError, BufferError, EOFError, LookupError,
OSError, ReferenceError, RuntimeError, StopAsyncIteration, StopIteration, SyntaxError, SystemError,
Warning, FloatingPointError, OverflowError, ZeroDivisionError, BytesWarning, DeprecationWarning, EncodingWarning,
FutureWarning, ImportWarning, PendingDeprecationWarning, ResourceWarning, RuntimeWarning, SyntaxWarning, UnicodeWarning,
UserWarning, BlockingIOError, ChildProcessError, ConnectionError,
FileExistsError, FileNotFoundError, InterruptedError, IsADirectoryError, NotADirectoryError,
PermissionError, ProcessLookupError, TimeoutError, IndentationError, ModuleNotFoundError,
RecursionError, UnboundLocalError, UnicodeError, BrokenPipeError,
ConnectionAbortedError, ConnectionRefusedError, ConnectionResetError,
TabError, UnicodeDecodeError, UnicodeEncodeError, UnicodeTranslateError,
ExceptionGroup, EnvironmentError,
# Misc
quit, exit,
copyright, credits, license, help,
# Dunder
__name__, __doc__, __package__, __loader__, __spec__, __build_class__, __import__,
__debug__,
Advanced Terms¶
Terms you may want to learn more about after getting the basics are:
* metaclass
* coroutine
* duck-typing
* docstring
* GIL
* hashable
* mapping
* immutable
* method resolution order
* virtual environment
* type annotation
* PEP
The official glossary is: https://docs.python.org/3/glossary.html
Python Package Structure / Importing¶
I’ve written a stackoverflow answer that contains good information about python packaging and how to handle importing external files.