让你相见恨晚的十个Python骚操作

In [1]: import __hello__
Hello world!

In [1]: x,y = y,x

In [24]: x = 10

In [25]: 5 < x < 20
Out[25]: True

In [26]: 11 < x < 20
Out[26]: False

In [2]: list = list(range(10))
# 取偶数
In [3]: even = [x for x in list if x % 2 == 0]

In [4]: even
Out[4]: [0, 2, 4, 6, 8]

In [5]: x = ['a', 'b', 'c', 'd', 'e', 'f', 'g']

In [6]: ''.join(x)
Out[6]: 'abcdefg'

In [2]: x
Out[2]: [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

# 取索引为 2 到 8 的值，步长为 2
In [4]: x[2:8:2]
Out[4]: [2, 4, 6]

# 步长为负值，表示从后面取值
In [6]: x[::-2]
Out[6]: [9, 7, 5, 3, 1]

In [7]: x = 'Hello Python!'

In [8]: x[::-1]
Out[8]: '!nohtyP olleH'

x = list(range(10))
for index, value in enumerate(x):
 print(index, value)

In [7]: a = [1,2,3]

In [8]: b = [4,5,6]

In [9]: c = [7,8,9]

In [16]: list(zip(a, b, c))
Out[16]: [(1, 4, 7), (2, 5, 8), (3, 6, 9)]

# 逆操作
In [18]: zz = (zip(a, b, c))

In [19]: x, y, z = zip(*zz)

In [20]: x,y,z
Out[20]: ((1, 2, 3), (4, 5, 6), (7, 8, 9))

# 合并列表相邻项
In [22]: a = [1, 2, 3, 4, 5, 6]

In [23]: list(zip(a[::2], a[1::2]))
Out[23]: [(1, 2), (3, 4), (5, 6)]

def outer(x):
 def inner(y):
  # 在内函数中 用到了外函数的变量
  nonlocal x
  x += y
  return x + y

 # 外函数的返回值是内函数的引用
 return inner

fun = outer(10)

print(fun(10)) # 30
print(fun(10)) # 40
print(fun(10)) # 50