# bad practice码n1 = input("enter a number : ")n2 = input("enter a number : ")n2 = input("enter a number : ")print(n1, n2, n3)

# good practicen1, n2, n3 = input("enter a number : ").split()print(n1, n2, n3)

size = "lg"color = "blue"price = 50# bad practiceif size == "lg" and color == "blue" and price < 100:    print("Yes, I want to but the product.")

# good practiceconditions = [    size == "lg",    color == "blue",    price < 100,]if all(conditions):    print("Yes, I want to but the product.")

# bad practicesize = "lg"color = "blue"price = 50if size == "lg" or color == "blue" or price < 100:    print("Yes, I want to but the product.")

# good practiceconditions = [    size == "lg",    color == "blue",    price < 100,]if any(conditions):    print("Yes, I want to but the product.")

print('odd' if int(input('Enter a number: '))%2 else 'even')

v1 = 100v2 = 200# bad practicetemp = v1v1 = v2v2 = temp

v1 = 100v2 = 200# good practicev1, v2 = v2, v1

print("John Deo"[::-1])

v1 = "madam" # is a palindrome stringv2 = "master" # is not a palindrome stringprint(v1.find(v1[::-1]) == 0) # Trueprint(v1.find(v2[::-1]) == 0) # False

name = "ali"age = 22# bad practicesif name:print(name)if name and age > 18:print("user is verified")

# a better approachprint(name if name else "")""" here you have to define the else condition too"""# good practice name and print(name)
age > 18 and name and print("user is verified")

lst = [1, 2, 3, 4, 3, 4, 4, 5, 6, 3, 1, 6, 7, 9, 4, 0]print(lst)unique_lst = list(set(lst))print(unique_lst)

lst = [1, 2, 3, 4, 3, 4, 4, 5, 6, 3, 1, 6, 7, 9, 4, 0]most_repeated_item = max(lst, key=lst.count)print(most_repeated_item)

numbers = [1,2,3,4,5,6,7]evens = [x for x in numbers if x % 2 is 0]odds = [y for y in numbers if y not in evens]cities = ['London', 'Dublin', 'Oslo']def visit(city):    print("Welcome to "+city)for city in cities:    visit(city)

def sum_of_squares(n1, n2)return n1**2 + n2**2print(sum_of_squares(2,3))# output: 13"""what ever if you want to pass, multiple args to the function as n number of args. so let's make it dynamic."""def sum_of_squares(*args):return sum([item**2 for item in args])# now you can pass as many parameters as you wantprint(sum_of_squares(2, 3, 4))print(sum_of_squares(2, 3, 4, 5, 6))

lst = ["blue", "lightblue", "pink", "orange", "red"]for idx, item in enumerate(lst):     print(idx, item)

names = ["john", "sara", "jim", "rock"]print(", ".join(names))

d1 = {"v1": 22, "v2": 33}d2 = {"v2": 44, "v3": 55}d3 = {**d1, **d2}print(d3)

{'v1': 22, 'v2': 44, 'v3': 55}

keys = ['a', 'b', 'c']vals = [1, 2, 3]zipped = dict(zip(keys, vals))

d = {    "v1": 80,    "v2": 20,    "v3": 40,    "v4": 20,    "v5": 10,}sorted_d = dict(sorted(d.items(), key=lambda item: item[1]))print(sorted_d)

from operator import itemgettersorted_d = dict(sorted(d.items(), key=itemgetter(1)))

sorted_d = dict(sorted(d.items(), key=itemgetter(1), reverse=True))

from pprint import pprintdata = {"name": "john deo","age": "22","address": {"contry": "canada", "state": "an state of canada :)", "address": "street st.34 north 12"},"attr": {"verified": True, "emialaddress": True},}print(data)pprint(data)

{'name': 'john deo', 'age': '22', 'address': {'contry': 'canada', 'state': 'an state of canada :)', 'address': 'street st.34 north 12'}, 'attr': {'verified': True, 'emialaddress': True}}{'address': {'address': 'street st.34 north 12','contry': 'canada','state': 'an state of canada :)'},'age': '22','attr': {'emialaddress': True, 'verified': True},'name': 'john deo'}

# 使用切片$ python -m timeit -n 1000000 -s 'import numpy as np' 'mylist=list(np.arange(0, 200))' 'mylist[::-1]'1000000 loops, best of 5: 15.6 usec per loop
# 使用reverse()$ python -m timeit -n 1000000 -s 'import numpy as np' 'mylist=list(np.arange(0, 200))' 'mylist.reverse()'1000000 loops, best of 5: 10.7 usec per loop