Comprehensive Python Tutorial: Data Types, Containers, Strings, and Custom Classes

Learning Python is a continuous process; this article reinforces the four major data types and demonstrates practical examples.

Numeric Types

Python treats all data as objects; common numeric objects are int , float , and bool .

<code>0xa5  # equals decimal 165</code>

<code>1.05e3  # 1050.0</code>

Container Types

Containers can hold multiple elements: list , tuple , dict , and set .

<code>lst = [1, 3, 5]  # list variable</code>

<code>tup = (1, 3, 5)  # tuple variable</code>

<code>dic = {'a': 1, 'b': 3, 'c': 5}  # dict variable</code>

<code>s = {1, 3, 5}  # set variable</code>

Examples include removing the smallest and largest values from a list and computing the mean, printing a 99‑multiplication table, and random sampling from a list.

<code>def score_mean(lst):
    lst.sort()
    lst2 = lst[1:-1]
    return round(sum(lst2) / len(lst2), 1)

lst = [9.1, 9.0, 8.1, 9.7, 19, 8.2, 8.6, 9.8]
score_mean(lst)  # 9.1</code>

<code>for i in range(1, 10):
    for j in range(1, i+1):
        print('%d*%d=%d' % (j, i, j*i), end='\t')
    print()</code>

<code>from random import randint, sample
lst = [randint(0, 50) for _ in range(100)]
lst_sample = sample(lst, 10)</code>

String Operations

Common string methods include strip , replace , join , title , and find .

<code>'  I love python\t\n  '.strip()  # 'I love python'</code>

<code>'i love python'.replace(' ', '_')  # 'i_love_python'</code>

<code>'_'.join(['book', 'store', 'count'])  # 'book_store_count'</code>

<code>'i love python'.title()  # 'I Love Python'</code>

<code>'i love python'.find('python')  # 7</code>

To check if one string is a rotation of another, test whether str1 is a substring of str2+str2 :

<code>def is_rotation(s1: str, s2: str) -> bool:
    if s1 is None or s2 is None:
        return False
    if len(s1) != len(s2):
        return False
    def is_substring(a, b):
        return a in b
    return is_substring(s1, s2 + s2)</code>

Regular‑expression password validation (6‑20 alphanumeric characters, no underscore):

<code>import re
pat = re.compile(r'[\da-zA-Z]{6,20}')
pat.fullmatch('n0passw0Rd')  # matches</code>

Custom Types

Define a class with class , use self for instance attributes, and explore magic methods.

<code>class Dog(object):
    pass

wangwang = Dog()</code>

Adding an __init__ method creates attributes:

<code>def __init__(self, name, dtype):
    self.name = name
    self.dtype = dtype</code>

Define methods such as shout :

<code>def shout(self):
    print("I'm %s, type: %s" % (self.name, self.dtype))</code>

Private attributes are prefixed with __ ; they can be accessed via property decorators for read‑only or read‑write behavior.

<code>class Book(object):
    def __init__(self, name, sale):
        self.__name = name
        self.__sale = sale
    @property
    def name(self):
        return self.__name
    @name.setter
    def name(self, new_name):
        self.__name = new_name</code>

Using property makes name behave like a regular attribute while controlling access.

- END -