Python syntax and common patterns – Not an exhaustive list, just a few things I find handy to keep in a cheat sheet.

Variables and Types

• Lists: ["a" , "b", "c"]
• Tuples: Immutable lists ("a", "b", "c")
• Dicts: key/value dictionaries/hashtable {"a": 1, "b":2}
• Sets: key-only dict {"a", "b"}
  • requires property uniqueness
  • Faster lookup for existence
  • unordered, mutable

List Methods

a.append()
a.reverse()

Dict Methods

d.get("i", "default") 
d.update({"j": 5}) # add to dict
d.keys() # iterable of keys
d.values() # iterable of values
d.items() # iterable of both

Loops

• List Comprehension: create new lists in loops

  original = ["A", "B", "C" ]
  converted = [
    i.lower() for i in original
  ]
  

Functions

• Lambda functions: one line functions

  cubed = lambda i: i**3
  

• Variable length arguments

  do_something(*args, **kwargs)
    for arg in args:
        #iterable of non-keys arguments
    for key, value in kwargs.items():
        # dict of keyed arguments, note items() to allow for iteration
  

Exception Handling

try: a.keys()
except Exception as e:
    print("err", e)