10个Python编程小技巧

1. 变量交换

a = 1
b = 2
a, b = b, a # 实现了对两个数的交换

a, b

(2, 1)

2. 字符串格式化

name = 'Jack'
country = 'China'
age = 18

# 1. 传统的字符串拼接（很繁杂）
print("Hi, I'm " + name + ". I'm from " + country + ". And I'm " + str(age) + " years old.")

# 2. 百分号语法
print("Hi, I'm %s. I'm from %s. And I'm %d years old." %(name, country, age))

# 3. format函数
print("Hi, I'm {}. I'm from {}. And I'm {} years old.".format(name, country, age))
# print("Hi, I'm {0}. Yes, I'm {0}!".format(name, country, age)) # 索引0为第一个参数

# 4. f-string写法
print(f"Hi, I'm {name}. I'm from {country}. And I'm {age} years old.")

Hi, I'm Jack. I'm from China. And I'm 18 years old.
Hi, I'm Jack. I'm from China. And I'm 18 years old.
Hi, I'm Jack. I'm from China. And I'm 18 years old.
Hi, I'm Jack. I'm from China. And I'm 18 years old.

3. Yield 语法

# 传统写法
def fibo(n):
    a = 0
    b = 1
    nums = []
    for _ in range(n):
        nums.append(a)
        a, b = b, a+b
    return nums

for i in fibo(6):
    print(i)

0
1
1
2
3
5

# 用Yield函数
def fibo_y(n):
    a = 0
    b = 1
    for _ in range(n):
        yield a
        a, b = b, a+b

for i in fibo_y(6):
    print(i)

0
1
1
2
3
5

4. 列表解析式

# 传统写法
fruit = ['apple', 'pear', 'pineapple', 'orange', 'banana']
for i in range(len(fruit)):
    fruit[i] = fruit[i].upper()

fruit

['APPLE', 'PEAR', 'PINEAPPLE', 'ORANGE', 'BANANA']

# 简洁写法
fruits = ['apple', 'pear', 'pineapple', 'orange', 'banana']
fruits = [x.upper() for x in fruits]

fruits

['APPLE', 'PEAR', 'PINEAPPLE', 'ORANGE', 'BANANA']

# 挑选出以‘p’字母开头的元素
fruits = ['apple', 'pear', 'pineapple', 'orange', 'banana']
filtered_fruits = [x for x in fruits if x.startswith('p')]

filtered_fruits

['pear', 'pineapple']

5. Enumerate函数

fruits = ['apple', 'pear', 'pineapple', 'orange', 'banana']
for i, x in enumerate(fruits):
    print(i, x)

0 apple
1 pear
2 pineapple
3 orange
4 banana

6.1 反向遍历

fruits = ['apple', 'pear', 'pineapple', 'orange', 'banana']
for i, x in enumerate(reversed(fruits)):
    print(i, x)

0 banana
1 orange
2 pineapple
3 pear
4 apple

6.2 按顺序遍历

fruits = ['apple', 'pear', 'pineapple', 'orange', 'banana']
for i, x in enumerate(sorted(fruits)):
    print(i, x)

0 apple
1 banana
2 orange
3 pear
4 pineapple

7. 字典的合并操作

a = {'ross': '12', 'xiaoming': '23'}
b = {'lilei': '34', 'zhangsan': '45'}
c = {**a, **b}

c

{'ross': '12', 'xiaoming': '23', 'lilei': '34', 'zhangsan': '45'}

8. 三元运算符

score = [56, 63, 80, 20, 100]
s = ['pass' if x>60 else 'fail' for x in score]
s

['fail', 'pass', 'pass', 'fail', 'pass']

9. 序列解包

name = 'Jack Tim'
first_name, last_name = name.split()
first_name, last_name

('Jack', 'Tim')

10. with语句

# 传统写法
f = open('haha.txt', 'r')
s = f.read()
f.close() # 不可省略，会占用资源

# with语句
with open('haha.txt', 'r') as f:
    s = f.read()

参考内容

https://www.bilibili.com/video/BV1kT4y1u72i?from=search&seid=12924391744156658505