Python 开发中有哪些高级技巧

列表推导式

>>> chars = [ c for c in 'python' ]
>>> chars['p', 'y', 't', 'h', 'o', 'n']

字典推导式

>>> dict1 = {'a': 1, 'b': 2, 'c': 3, 'd': 4, 'e': 5}
>>> double_dict1 = {k:v*2 for (k,v) in dict1.items()}
>>> double_dict1{'a': 2, 'b': 4, 'c': 6, 'd': 8, 'e': 10}

集合推导式

>>> set1 = {1,2,3,4}
>>> double_set = {i*2 for i in set1}
>>> double_set{8, 2, 4, 6}

合并字典

>>> x = {'a':1,'b':2}
>>> y = {'c':3, 'd':4}
>>> z = {**x, **y}
>>> z{'a': 1, 'b': 2, 'c': 3, 'd': 4}

复制列表

>>> nums = [1,2,3]
>>> nums[::][1, 2, 3]
>>> copy_nums = nums[::]
>>> copy_nums[1, 2, 3]

反转列表

>>> reverse_nums = nums[::-1]
>>> reverse_nums[3, 2, 1]

PACKING / UNPACKING

变量交换

>>> a,b = 1, 2
>>> a ,b = b,a
>>> a2
>>> b1

高级拆包

>>> a, *b = 1,2,3
>>> a1
>>> b[2, 3]

或者

>>> a, *b, c = 1,2,3,4,5
>>> a1
>>> b[2, 3, 4]
>>> c5

函数返回多个值(其实是自动 packing 成元组)然后 unpacking 赋值给4个变量

>>> def f():... return 1, 2, 3, 4...
>>> a, b, c, d = f()
>>> a1
>>> d4

列表合并成字符串

>>> " ".join(["I", "Love", "Python"])'I Love Python'

链式比较

>>> if a > 2 and a < 5:... pass...
>>> if 2

yield from#
没有使用 field fromdef dup(n): for i in range(n): yield i yield i#
使用yield fromdef dup(n): for i in range(n): yield from [i, i]for i in dup(3): print(i)
>>>001122in 代替 or

>>> if x == 1 or x == 2 or x == 3:... pass..
.>>> if x in (1,2,3):... pass

字典代替多个if

elsedef fun(x):
if x == 'a': return 1
elif x == 'b': return 2 else:
return Nonedef fun(x):
return {"a": 1, "b": 2}.get(x)

有下标索引的枚举

>>> for i, e in enumerate(["a","b","c"]):...
print(i, e)...0 a1 b2 c

生成器

注意区分列表推导式，生成器效率更高

>>> g = (i**2 for i in range(5))
>>> g at 0x10881e518>
>>> for i in g:... print(i)...014916