20个非常有用的单行Python代码

这篇博客将介绍20个Python一行代码。这些单行代码将节省时间，并使代码看起来更清晰、更易读。

1. 单行for循环
2. 单行while循环
3. 单行IF else语句
4. 单行合并词典
5. 单行函数：三元运算符或者lambda函数
6. 单行递归
7. 单行过滤数组
8. 单行异常处理
9. 单行数组转dict
10. 多变量单行赋值
11. 单行交换值
12. 单行排序
13. 单行读文件
14. 单行类
15. 单行分号
16. 单行print
17. 单行map
18. 单行代码：del删除列表多个元素
19. 单行打印图案 print+* 实现多次相同的打印
20. 单行代码找到一个数范围内的素数

#  20个有趣的单行python代码
# one_line.py

# 1. 单行for循环

mylist = [200, 300, 400, 500]
# 单行循环
result = []
for x in mylist:
    if x > 250:
        result.append(x)
print(result)  # [300, 400, 500]
# 一行代码方式
result = [x for x in mylist if x > 250]
print(result)  # [300, 400, 500]

# 2. 单行while循环
# Method 1 单个语句
# while True: print(1)  # infinite 1
# Method 2 多个语句
x = 0
while x < 5: print(x); x = x + 1  # 0 1 2 3 4 5

# 3. 单行IF else语句
# 要在一行中编写 IF Else 语句，我们将使用三元运算符。三元的语法是“[on true] if [expression] else [on false]”。
# Example 1 if else
print("Yes") if 8 > 9 else print("No")  # No
# Example 2 if elif else
E = 2
print("High") if E == 5 else print("数据工作室") if E == 2 else print("Low")  # Data STUDIO

# Example 3 only if
if 3 > 2: print('完全正确')  # 完全正确

# 4. 单行合并词典
d1 = {'A': 1, 'B': 2}
d2 = {'C': 3, 'D': 4}
# Method1
d1.update(d2)
print(d1)  # { 'A': 1, 'B': 2, 'C': 3, 'D': 4}
# Method2
d3 = {**d1, **d2}
print(d3)  # {'A': 1, ' B'：2，'C'：3，'D'：4}


# 5. 单行函数：三元运算符或者lambda函数
# Function in one line
# Method1
def fun(x): return True if x % 2 == 0 else False


print(fun(2))  # False
# Method2
fun = lambda x: x % 2 == 0
print(fun(2))  # 真
print(fun(3))  # 假


# 6. 单行递归
# Fibonaci 单行递归示例
def Fib(x): return 1 if x in {0, 1} else Fib(x - 1) + Fib(x - 2)


print(Fib(5))  # 8
print(Fib(15))  # 987

# 7.在一行中过滤数组
mylist = [2, 3, 5, 8, 9, 12, 13, 15]
# Normal way
result = []
for x in mylist:
    if x % 2 == 0:
        result.append(x)
print(result)  # [2, 8, 12]
# 单行方法
result = [x for x in mylist if x % 2 == 0]
print(result)  # [2, 8, 12]

# 8. 单行异常处理
try:
    print(x1)
except:
    print("Error")
# Single line way
exec('try:print(x) \nexcept:print("Error")')  # Error

# 9. 单行数组转dict
# Dictionary in one line
mydict = ["John", "Peter", "Mathew", "Tom"]
mydict = dict(enumerate(mydict))
print(mydict)  # {0: 'John', 1: 'Peter', 2: 'Mathew', 3: 'Tom'}

# 10. 多变量单行赋值
x = 5
y = 7
z = 10
print(x, y, z)  # 5 7 10
# Single line way
a, b, c = 5, 7, 10
print(a, b, c)  # 5 7 10

# 11. 单行交换值
v1 = 100
v2 = 200
temp = v1
v1 = v2
v2 = temp
print(v1, v2)  # 200 100
# One-line value swapping
v1, v2 = v2, v1
print(v1, v2)  # 200 100

# 12. 单行排序
mylist = [32, 22, 11, 4, 6, 8, 12]
# Method1
mylist.sort()
print(mylist)  # # [4, 6, 8, 11, 12, 22, 32]
print(sorted(mylist))  # [4, 6, 8, 11, 12, 22, 32]

# 13. 单行读文件
try:
    with open("log_demo.py", "r") as file:
        data = file.readline()
        print(data)  # Hello world
    # Single line way
    data = [line.strip() for line in open("log_demo.py", "r")]
    print(data)  # ['hello world', 'Hello Python']
except:
    print('error')


# 14. 单行类
class Emp:
    def __init__(self, name, age):
        self.name = name
        self.age = age


emp1 = Emp("a44", 22)
print(emp1.name, emp1.age)  #
# Single line way
# Method 1 Lambda with Dynamic Attributes

Emp = lambda: None;
Emp.name = "a44";
Emp.age = 22
print(Emp.name, Emp.age)

# Method 2
from collections import namedtuple

Emp = namedtuple('Emp', ["name", "age"])("a44", 22)
print(Emp.name, Emp.age)

# 15.单行分号
a = "Python";b = "编程";c = "语言";print(a, b, c)
# Python 编程语言

# 16.单行print
for x in range(1, 5):
    print(x)  # 1 2 3 4
# Single line way
print(*range(1, 5))  # 1 2 3 4
print(*range(1, 6))  # 1 2 3 4 5

# 17.单行map
print(list(map(lambda a: a + 2, [5, 6, 7, 8, 9, 10])))
# [7, 8, 9, 10, 11, 12]

# 18.单行代码：del删除列表多个元素
mylist = [100, 200, 300, 400, 500]
del mylist[1:: 2]
print(mylist)  # [100, 300, 500]

# 19. 单行打印图案 print+* 实现多次相同的打印
print('')  # print #  
# Single line way
print('' * 3)  #       print ( ' ' * 2 ) #    打印( '' * 1 ) # 

# 20. 单行代码找到一个数范围内的素数
print(list(filter(lambda a: all(a % b != 0 for b in range(2, a)),
                  range(2, 20))))
# [2, 3, 5, 7, 11, 13, 17, 19]

参考

• https://medium.com/@chenyumei8866/20-extremely-useful-single-line-python-codes-bc553ea4832a