1. Python Useful Functions and Methods
Peter Wad Sackett

2. Nothing more to learn ?
There are quite a few built-in functions not mentioned yet, see
So far has been mentioned 14 out of 68:
dict(), float(), format(), input(), int(), len(), list(), open(), print(), range(), reversed(), set(), sorted() str() & tuple()
Many of the unmentioned functions works with python’s object model or the inner workings of python.
Useful for advanced python code.

3. Nice to know built-in functions
The following are nice to know for a beginner:
abs(number) returns absolute value of a number
dir(object) returns info on an object
enumerate(iterable) returns an enumerated list of tuples
help(string) returns help in the subject given
id(object) returns the id of an object, guaranteed to be unique
iter(iterable) returns an iterable – dicts as key/value tuples
map(function, iterable) the function is applied on the iterable
max(iterable) returns the maximum value
min(iterable) returns the minimum value
round(number) rounds a number
sum(iterable) returns the sum of the iterable
zip(iterables) returns a list of tubles of the input in ”pairs”

4. Built-in data types A useful sequence method:
sequencetype.count(item) returns the number of occurences
New data types: bytearray and frozenset
Bytearrays are like mutable strings and supports all string methods. They are more efficient when your strings change.
name = bytearray(’Peter’)
Frozensets are immutable sets and supports all set methods, that does not change the frozenset, obviously.
Can be used as keys in dicts and sets.
Frozensets are to sets, what tuples are to lists.
fruits = frozenset(’apple’, ’banana’, ’cherry’, ’date’)

5. Standard libraries
Python has many standard libraries, far too many to memorize.
Each library contains several functions, all relevant and appropiate to the core functionality of the library. You won’t find string functions in the math library.
Learn to find what you need from the list.
In the course the following standard libraries have been used:
string – string operations
re – regular expressions
math – mathmatical functions
os – operating system interfaces
sys – system specific functions
Some new ones which are surprisingly often useful:
random – pseudo random numbers
copy – shallow and deep copy operations