python 推导式

最新推荐文章于 2025-08-01 15:52:43 发布

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最新推荐文章于 2025-08-01 15:52:43 发布

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文章标签： python 开发语言

本文链接：https://blog.youkuaiyun.com/nbbscdd/article/details/128493148

本文深入探讨了Python编程中的列表、元组、字典和集合推导式，通过示例展示了它们的用法和功能。从简单的数值操作到复杂的嵌套结构，这些推导式极大地提高了代码的简洁性和效率。同时，还介绍了元组推导式、字典推导式和集合推导式的应用场景。

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#推导式
'''
# **列表推导式**
[ expr for value in collection [if condition] ]
'''
x = [-4, -2, 0, 2, 4]
y = [a * 2 for a in x]
print(y)# [-8, -4, 0, 4, 8]
print("--"*20)
x = [i ** 2 for i in range(1, 10)]
print(x)# [1, 4, 9, 16, 25, 36, 49, 64, 81]
print("--"*20)
a = [(i, j) for i in range(0, 3) for j in range(0, 3)]
print(a)
# [(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]
print("--"*20)
a = [(i, j) for i in range(0, 3) if i < 1 for j in range(0, 3) if j > 1]
print(a)
# [(0, 2)]
print("--"*20)
'''**元组推导式**
( expr for value in collection [if condition] )
'''
a = (x for x in range(10))
print(a)
# <generator object <genexpr> at 0x0000025BE511CC48>
print(tuple(a))
# (0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
print("--"*20)
'''字典推导式

{ key_expr: value_expr for value in collection [if condition] }'''
b = {i: i % 2 == 0 for i in range(10) if i % 3 == 0}
print(b)
# {0: True, 3: False, 6: True, 9: False}
print("--"*20)
'''集合推导式

{ expr for value in collection [if condition] }'''

c = {i for i in [1, 2, 3, 4, 5, 5, 6, 4, 3, 2, 1]}
print(c)
# {1, 2, 3, 4, 5, 6}
print("--"*20)
'''其他推导式'''
s = sum([i for i in range(101)])
print(s)  # 5050
s = sum((i for i in range(101)))
print(s)  # 5050

'''
[-8, -4, 0, 4, 8]
----------------------------------------
[1, 4, 9, 16, 25, 36, 49, 64, 81]
----------------------------------------
[(0, 0), (0, 1), (0, 2), (1, 0), (1, 1), (1, 2), (2, 0), (2, 1), (2, 2)]
----------------------------------------
[(0, 2)]
----------------------------------------
<generator object <genexpr> at 0x0000017C0EA6C048>
(0, 1, 2, 3, 4, 5, 6, 7, 8, 9)
----------------------------------------
{0: True, 3: False, 6: True, 9: False}
----------------------------------------
{1, 2, 3, 4, 5, 6}
----------------------------------------
5050
5050

'''