13个你可能未使用过的Python特性分享

# 列表Stepping
data = [10, 20, 30, 40, 50]
print(data[::2]) # [10, 30, 50]
print(data[::3]) # [10, 40]
# 使用 stepping 翻转列表
print(data[::-1]) # [50, 40, 30, 20, 10]

# 查找方法
x = "Python"
y = "Hello From Python"
print(x.find("Python")) # 0
print(y.find("From"))  # 6
print(y.find("From Python")) #6

# Iter() 
values = [1, 3, 4, 6]
values = iter(values) 
print(next(values)) # 1 
print(next(values)) # 3 
print(next(values)) # 4 
print(next(values)) # 6

# Doctest 
from doctest import testmod 
def Mul(x, y) -> int: 
   """
   这个函数返回 x 和 y 参数的 mul
   调用函数，然后是预期的输出：
   >>> Mul(4, 5) 
   20 
   >> > Mul(19, 20) 
   39 
   """ 
   return x * y 
# 调用 testmod 函数
testmod(name='Mul', verbose=True)
输出：
Trying:
    Mul(4, 5)
Expecting:
    20
ok
Trying:
    Mul(19, 20)
Expecting:
    39
**********************************************************************
File "__main__", line 10, in Mul.Mul
Failed example:
    Mul(19, 20)
Expected:
    39
Got:
    380
1 items had no tests:
Mul
**********************************************************************
1 items had failures:
   1 of   2 in Mul.Mul
2 tests in 2 items.
1 passed and 1 failed.
***Test Failed*** 1 failures.

# Yield声明
def func(): 
    print(1) 
    yield 1 
    print(2) 
    yield 2 
    print(3) 
    yield 3 
    
for call in func(): 
    pass# 输出
# 1 
# 2 
# 3

# 处理字典中的缺失值
dict_1 = {1："x"，2："y"}
# 不要使用get
print(dict_1[3]) # key error
# 使用get  
print(dict_1.get(3)) #  None

# 为/否则  
for x in range(5): 
    print(x) 
else: 
    print("Loop Completed") # 执行# While / Else 
i = 0 
while i < 5: 
    break 
else: 
    print("Loop Completed") # 未执行

# 命名格式化字符串
a = "Python" 
b = "工作"# Way 1 
string = "I looking for a {} Programming {}".format(a, b) 
print(string) # I looking for a Python Programming Job

#Way 2 
string = f"I looking for a {a} Programming {b}" 
print(string) # I looking for a Python Programming Job

# 设置递归限制
import sys
sys.setrecursionlimit = 2000
print(sys.getrecursionlimit) # 2000

# 条件参数
x = 5 if 2 > 4 else 2
print(x) # 2
y = 10 if 32 > 41 else 24
print(y) # 24

# 参数解包  
def func(x, y): 
    print(x, y) 
list_1 = [100, 200] 
dict_1 = {'x':300, 'y':400} 
func(*list_1) 
func(**dict_1)  
# 输出
# 100 200 
# 300 400

import __hello__

# 多行字符串
str1= "你是否正在寻找Python学习材料" \ 
      "欢迎来到 " \
      "本公众号"
print(str1) 
# 你是否正在寻找Python学习材料，欢迎来到 本公众号