Python开发中有哪些高级技巧

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Python 开发中有哪些高级技巧?这是知乎上一个问题，我总结了一些常见的技巧在这里，可能谈不上多高级，但掌握这些至少可以让你的代码看起来 Pythonic 一点。如果你还在按照类C语言的那套风格来写的话，在 code review 恐怕会要被吐槽了。

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 >>> a 2 >>> b 1

高级拆包

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

或者

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

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() >>> a 1 >>> d 4

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 from def dup(n):     for i in range(n):         yield i         yield i  # 使用yield from def dup(n):     for i in range(n):     yield from [i, i]  for i in dup(3):     print(i)  >>> 0 0 1 1 2 2
in 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 else
def fun(x):     if x == 'a':         return 1     elif x == 'b':         return 2     else:         return None  def 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 a 1 b 2 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) ... 0 1 4 9 16
默认字典 defaultdict
>>> d = dict() >>> d['nums'] KeyError: 'nums' >>>  >>> from collections import defaultdict >>> d = defaultdict(list) >>> d["nums"] []
字符串格式化
>>> lang = 'python' >>> f'{lang} is most popular language in the world' 'python is most popular language in the world'
列表中出现次数最多的元素
>>> nums = [1,2,3,3] >>> max(set(nums), key=nums.count) 3  或者 from collections import Counter >>> Counter(nums).most_common()[0][0] 3
读写文件
>>> with open("test.txt", "w") as f: ...     f.writelines("hello")
判断对象类型，可指定多个类型
>>> isinstance(a, (int, str)) True
类似的还有字符串的 startswith，endswith
>>> "http://foofish.net".startswith(('http','https')) True >>> "https://foofish.net".startswith(('http','https')) True
__str__ 与 __repr__ 区别
>>> str(datetime.now()) '2018-11-20 00:31:54.839605' >>> repr(datetime.now()) 'datetime.datetime(2018, 11, 20, 0, 32, 0, 579521)'
前者对人友好，可读性更强，后者对计算机友好，支持 obj == eval(repr(obj))
使用装饰器
def makebold(f): return lambda: "" + f() + ""  def makeitalic(f): return lambda: "" + f() + ""  @makebold @makeitalic def say(): return "Hello"  >>> say() Hello
不使用装饰器，可读性非常差
def say(): return "Hello"  >>> makebold(makeitalic(say))() Hello
上述就是小编为大家分享的Python开发中有哪些高级技巧了，如果刚好有类似的疑惑，不妨参照上述分析进行理解。如果想知道更多相关知识，欢迎关注行业资讯频道。