Master Python’s Core Data Structures: Lists, Tuples, Sets, and Dictionaries Explained

Python provides several built‑in data structures that are essential for everyday programming.

List

Lists are ordered, mutable collections defined with square brackets. Elements can be of any type and duplicate values are allowed.

In [1]: list1 = ['wellcom','to','the','sjwjyaisf1688']
Out[1]: ['wellcom', 'to', 'the', 'sjwjyaisf1688']
In [2]: list2 = ['wellcom','to','the','sjwjyaisf1688',6,6,6]
Out[2]: ['wellcom', 'to', 'the', 'sjwjyaisf1688', 6, 6, 6]
# create with list()
In [3]: list(['xiao','xiao','wa','jue','ji',666])
Out[3]: ['xiao', 'xiao', 'wa', 'jue', 'ji', 666]
In [4]: list('666')
Out[4]: ['6', '6', '6']
# concatenation
In [5]: ['wellcom','to','te'] + ['xiao','xiao','ji','666']
Out[5]: ['wellcom', 'to', 'te', 'xiao', 'xiao', 'ji', '666']
# append
In [6]: list2 = ['a','b','c']
In [7]: list2.append('d')
Out[7]: ['a', 'b', 'c', 'd']
# extend
In [8]: list2.extend(['e','f'])
Out[8]: ['a', 'b', 'c', 'd', 'e', 'f']

Tuple

Tuples are ordered, immutable collections. They are defined by commas, optionally enclosed in parentheses.

In [1]: tuple1 = 1,2,3
In [2]: tuple2 = "sjwjyaisf1688","xiaoxiaowajueji666"
In [3]: tuple3 = (1,2,3,4)
In [4]: tuple4 = ()
In [5]: tuple5 = (1,)
In [6]: print(tuple1,tuple2,tuple3,tuple4,tuple5)
Out: (1, 2, 3) ('sjwjyaisf1688', 'xiaoxiaowajueji666') (1, 2, 3, 4) () (1,)
# concatenation
In [7]: (1,2,3) + (4,5,6)
Out[7]: (1, 2, 3, 4, 5, 6)

Attempting to assign to a tuple element raises a TypeError because tuples are immutable.

Set

Sets are unordered collections of unique elements, created with curly braces or the set() constructor.

In [1]: drink = {'water','milk','lemonade','beer','sprite'}
Out[1]: {'beer', 'lemonade', 'milk', 'sprite', 'water'}
In [2]: drink = set(['water','milk','lemonade','beer','sprite','milk'])
Out[2]: {'beer', 'lemonade', 'milk', 'sprite', 'water'}
A = {1,2,3,4,5,6}
B = {3,4,5}
# difference
In [3]: A - B
Out[3]: {1, 2, 6}
# union
In [4]: A | B
Out[4]: {1, 2, 3, 4, 5, 6}
# intersection
In [5]: A & B
Out[5]: {3, 4, 5}

Dictionary

Dictionaries store key‑value pairs and provide fast lookup. Keys must be unique.

In [1]: dict1 = {'xiaoming':24,'xiaofang':28,'zhangsan':21,'wangwu':27}
Out[1]: {'wangwu': 27, 'xiaofang': 28, 'xiaoming': 24, 'zhangsan': 21}
In [2]: dict1.keys()
Out[2]: dict_keys(['xiaoming','xiaofang','zhangsan','wangwu'])
In [3]: dict1.values()
Out[3]: dict_values([24,28,21,27])
In [4]: dict1['xiaoming']
Out[4]: 24
# duplicate key overwrites previous value
In [5]: dict2 = {'xiaoming':24,'xiaofang':28,'zhangsan':21,'wangwu':27,'xiaoming':25}
Out[5]: {'xiaoming': 25, 'xiaofang': 28, 'zhangsan': 21, 'wangwu': 27}