Python has many built-in functions and methods. Below or online you can find a overview of these functions and methods. The relevant ones are either already explained in other chapters, or after the table.
partly exam relevant
Only some of these Functions and Methods ae actually exam relevant.
Overview
| Category | Function/Method |
|---|---|
| Type & Casting | type(), int(), float(), str(), bool(), list(), tuple(), dict(), set(), frozenset(), complex(), bytes(), bytearray(), memoryview(), ord(), chr(), ascii() |
| Mathematical | abs(), round(), pow(), divmod(), sum(), min(), max() |
| Iterables & Sequences | len(), sorted(), reversed(), enumerate(), zip(), filter(), map(), all(), any() |
| String Handling | .lower(), .upper(), .strip(), .split(), .join(), .replace(), .startswith(), .endswith(), .find(), .count() |
| List Methods | .append(), .extend(), .insert(), .remove(), .pop(), .index(), .count(), .sort(), .reverse(), .copy(), .clear() |
| Set Methods | .add(), .remove(), .discard(), .pop(), .union(), .intersection(), .difference(), .symmetric_difference(), .issubset(), .issuperset(), .copy(), .clear() |
| Dictionary Methods | .keys(), .values(), .items(), .get(), .pop(), .update(), .copy(), .clear() |
| File Handling | open(), .read(), .readline(), .readlines(), .write(), .writelines(), .close() |
| Object & Class Handling | isinstance(), issubclass(), getattr(), setattr(), hasattr(), delattr(), dir(), vars(), super() |
| System & Debugging | print(), input(), exit(), id(), hash(), help(), repr(), callable(), exec(), eval(), globals(), locals() |
Mathematical Functions
abs(x)
Returns the absolute value of x.
print(abs(-2)) # -> 2
print(abs(3 + 4j)) # -> 5round(number, ndigits=None)
Rounds number to ndigits decimal places (default: 0).
print(round(4.56)) # -> 5
print(round(3.14159, 2)) # -> 3.14
print(round(123456, -3)) # -> 123000sum(iterable, start=0)
Returns the sum of iterable, plus a start value (default: 0).
print(sum([1, 2, 3])) # -> 6
print(sum((), start=5)) # -> 5
print(sum({2, -2, 3, -4}, start=2)) # -> 1min/max(iterable, *, key=None, default=None)
Returns the smallest/largest item in iterable or the default if empty. The key can take a function that will be executed for each element to determine its value.
print(min([3, 1, 4])) # -> 1
print(max([3, 1, 4])) # -> 4
print(min(["apple", "banana"], key=len)) # -> apple
print(max(["apple", "banana"], key=len)) # -> banana
people = [{"name": "Andreas", "size": 181}, {"name": "Tom", "size": 168}]
print(min(people, key=lambda x: x["size"])) # -> {'name': 'Tom', 'size': 168}
print(max(people, key=lambda x: x["size"])) # -> {'name': 'Andreas', 'size': 181}Collections
len(obj)
Returns the number of items in a collection obj.
print(len([1, 2, 3])) # -> 3
print(len("some text")) # -> 9
print(len("a b\n")) # -> 4
print(len([1, (2, 3)])) # -> 2.index(sub, start=0, stop=None)
Returns the index of the first occurrence of sub in the collection. Throws a Value Error if value is not in the list. You can use start and stop to only search in a slice of the collection.
print([4, 2, 7, 3, 1, 3].index(3)) # -> 3sorted(iterable, *, key=None, reverse=False)
Returns a new sorted list from iterable. Default is ascending (smallest to largest), but you can reverse it. The key can take a function that will be executed for each element to determine the value that will be used for sorting. You can also sort a existing list in place with the method .sort().
print(sorted([3, 1, 2])) # -> [1, 2, 3]
people = [{"name": "Andreas", "size": 181}, {"name": "Tom", "size": 168}]
print(sorted(people, key=lambda x: x["size"])) # -> [{'name': 'Tom', 'size': 168}, {'name': 'Andreas', 'size': 181}]reversed(iterable)
Returns an iterator thats the reversed order of the initial iterable. You can also reverse a existing list in place with the method .reverse().
print(list(reversed([1, 2, 3]))) # -> [3, 2, 1]enumerate(iterable, start=0)
Returns an iterator with (index, value) pairs from iterable. You can set a start value for indexing (default: 0)
print(list(enumerate([33, 66, 99]))) # -> [(0, 33), (1, 66), (2, 99)]
print(list(enumerate("abc", start=10))) # -> [(10, 'a'), (11, 'b'), (12, 'c')]zip(*iterables, strict=False)
Combines iterables element-wise. The number of combined objects will be the same as the number of objects in the smallest iterable. If strict, then raise a ValueError if not all iterables have the same length.
print(list(zip([1, 2], ["a", "b"]))) # -> [(1, 'a'), (2, 'b')]
print(list(zip([1,2,3], (1j,2j,3j,4j), "abcdef"))) # -> [(1, 1j, 'a'), (2, 2j, 'b'), (3, 3j, 'c')]filter(function, iterable)
Filters so that only elements for whichfunction returns True are remaining.
print(list(filter(lambda x: x>0, [-1, 2, -3, 4]))) # -> [2, 4]map(function, iterable)
Applies function to each item.
print(list(map(lambda x: 10*x, [1, 2, 3]))) # -> [10, 20, 30]
print(list(map(str, [1, 2, 3]))) # -> ['1', '2', '3']String Methods
.lower() / .upper()
Returns string in all lower-/uppercase characters.
print("Hello".lower()) # -> hello
print("Hello".upper()) # -> HELLO.strip(character="")
Returns a string without all characters at the start end end of the initial string. By default removes all whitespace type characters. Everything between the two outer most characters that are not in the characters to remove will be kept. You can use .lstrip()/.rstrip() to only remove from the start/end.
print(" \n test message \n".strip()) # -> test message
print(" \n test message \n".lstrip()) # -> test message \n
print(" \n test message \n".rstrip()) # -> \n test message
print(" \n, ,,;; test, message,, ,;; \n".strip(" \n,;")) # -> test message.split(sep=" ", maxsplit=-1)
Splits a string into a list. Whenever sep occurs, a new element will start. Default sep is a space ” “. maxsplit is the maximum number of splits, or -1 for unlimited.
print("hello world text".split()) # -> ['hello', 'world', 'text']
print("some | random | string".split(sep=" | ")) # -> ['some', 'random', 'string']
print("some long hello world text".split(maxsplit=2)) # -> ['some', 'long', 'hello world text'].join(iterable)
Joins string elements from an iterable with the string as separator.
print("".join(["a", "b", "c"])) # -> abc
print("-".join(["a", "b", "c"])) # -> a-b-c.find(sub, start=0, stop=None)
Returns the index of the first occurrence of sub, or -1 if not found. You can use start and stop to only search in a slice of the string.
print("hello".find("l")) # -> 2.count(sub, start=0, end=None)
Counts how often sub occurs. You can use start and end to only search in a slice of the string
print("banana".count("a")) # -> 3.replace(old, new, count=-1)
Replaces the old string with a new string. It will replace a maximum of count times, or -1 for unlimited.
print("hello".replace("l", "x")) # -> hexxo
print("hellllllo".replace("l", "x", 2)) # -> hexxllllo
print("hellllllo".replace("lll", "l")) # -> hello.startswith(string) / .endswith(string)
Checks if a string starts or ends with a substring.
print("hello".startswith("he")) # -> True
print("hello".startswith("lo")) # -> False
print("hello".endswith("lo")) # -> TrueList Methods
Add Elements
Add elements by.append(value) element with value at the end of the list, extend(iterable) at the end with multiple values from iterable, or.insert(index, value) element with value at index.
l = [1]
l.append(2)
print(l) # -> [1, 2]
l.extend([3, 4, 2])
print(l) # -> [1, 2, 3, 4, 2]
l.insert(1, 5)
print(l) # -> [1, 5, 2, 3, 4, 2]Remove Elements
.remove() first element with specific value, .pop() (remove and return) element at index, or .clear() the whole list.
l = [1, 5, 2, 3, 4, 2]
print(l.remove(2)) # -> None
print(l) # -> [1, 5, 3, 4, 2]
print(l.pop()) # -> 2
print(l) # -> [1, 5, 3, 4]
print(l.clear()) # -> None
print(l) # -> [1, 5, 3, 4].copy()
Returns a shallow copy.
Dictionary Methods
.keys() returns a view of all keys in the dictionary. .values() returns a view of all values in the dictionary. .items() returns a view of (key, value) pairs.
d = {'a': 1, 'b': 2}
print(list(d.keys())) # -> ['a', 'b']
print(list(d.values())) # -> [1, 2]
print(list(d.items())) # -> [('a', 1), ('b', 2)]Object & Class Handling
isinstance(obj, classinfo), issubclass(cls, classinfo)
Check instance or subclass relations.
getattr(obj, name, default), setattr(obj, name, value), hasattr(obj, name), delattr(obj, name)
Get, set, check, or delete attributes dynamically.
System & Debugging
exit()
Exits the interpreter.
help(obj)
Shows help.
repr(obj)
Returns a string representation.
callable(obj)
Checks if obj is callable.
exec(code), eval(expr)
Executes Python code.
globals(), locals()
Returns the global or local namespace.