15个Pythonic的代码示例(值得收藏)
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2022-06-22 11:42:29
python由于语言的简洁性,让我们以人类思考的方式来写代码,新手更容易上手,老鸟更爱不释手。要写出 pythonic(优雅的、地道的、整洁的)代码,还要平时多观察那些大牛代码,github 上有很多...
python由于语言的简洁性,让我们以人类思考的方式来写代码,新手更容易上手,老鸟更爱不释手。
要写出 pythonic(优雅的、地道的、整洁的)代码,还要平时多观察那些大牛代码,github 上有很多非常优秀的源代码值得阅读,比如:requests、flask、tornado,这里小明收集了一些常见的 pythonic 写法,帮助你养成写优秀代码的习惯。
01. 变量交换
bad
tmp = a a = b b = tmp
pythonic
a,b = b,a
02. 列表推导
bad
my_list = [] for i in range(10): my_list.append(i*2)
pythonic
my_list = [i*2 for i in range(10)]
03. 单行表达式
虽然列表推导式由于其简洁性及表达性,被广受推崇。
但是有许多可以写成单行的表达式,并不是好的做法。
bad
print 'one'; print 'two' if x == 1: print 'one' if <complex comparison> and <other complex comparison>: # do something
pythonic
print 'one' print 'two' if x == 1: print 'one' cond1 = <complex comparison> cond2 = <other complex comparison> if cond1 and cond2: # do something
04. 带索引遍历
bad
for i in range(len(my_list)): print(i, "-->", my_list[i])
pythonic
for i,item in enumerate(my_list): print(i, "-->",item)
05. 序列解包
pythonic
a, *rest = [1, 2, 3] # a = 1, rest = [2, 3] a, *middle, c = [1, 2, 3, 4] # a = 1, middle = [2, 3], c = 4
06. 字符串拼接
bad
letters = ['s', 'p', 'a', 'm'] s="" for let in letters: s += let
pythonic
letters = ['s', 'p', 'a', 'm'] word = ''.join(letters)
07. 真假判断
bad
if attr == true: print 'true!' if attr == none: print 'attr is none!'
pythonic
if attr: print 'attr is truthy!' if not attr: print 'attr is falsey!' if attr is none: print 'attr is none!'
08. 访问字典元素
bad
d = {'hello': 'world'} if d.has_key('hello'): print d['hello'] # prints 'world' else: print 'default_value'
pythonic
d = {'hello': 'world'} print d.get('hello', 'default_value') # prints 'world' print d.get('thingy', 'default_value') # prints 'default_value' # or: if 'hello' in d: print d['hello']
09. 操作列表
bad
a = [3, 4, 5] b = [] for i in a: if i > 4: b.append(i)
pythonic
a = [3, 4, 5] b = [i for i in a if i > 4] # or: b = filter(lambda x: x > 4, a)
bad
a = [3, 4, 5] for i in range(len(a)): a[i] += 3
pythonic
a = [3, 4, 5] a = [i + 3 for i in a] # or: a = map(lambda i: i + 3, a)
10. 文件读取
bad
f = open('file.txt') a = f.read() print a f.close()
pythonic
with open('file.txt') as f: for line in f: print line
11. 代码续行
bad
my_very_big_string = """for a long time i used to go to bed early. sometimes, \ when i had put out my candle, my eyes would close so quickly that i had not even \ time to say “i'm going to sleep.”""" from some.deep.module.inside.a.module import a_nice_function, another_nice_function, \ yet_another_nice_function
pythonic
my_very_big_string = ( "for a long time i used to go to bed early. sometimes, " "when i had put out my candle, my eyes would close so quickly " "that i had not even time to say “i'm going to sleep.”" ) from some.deep.module.inside.a.module import ( a_nice_function, another_nice_function, yet_another_nice_function)
12. 显式代码
bad
def make_complex(*args): x, y = args return dict(**locals())
pythonic
def make_complex(x, y): return {'x': x, 'y': y}
13. 使用占位符
pythonic
filename = 'foobar.txt' basename, _, ext = filename.rpartition('.')
14. 链式比较
bad
if age > 18 and age < 60: print("young man")
pythonic
if 18 < age < 60: print("young man")
理解了链式比较操作,那么你应该知道为什么下面这行代码输出的结果是 false
>>> false == false == true false
15. 三目运算
这个保留意见。随使用习惯就好。
bad
if a > 2: b = 2 else: b = 1 #b = 2
pythonic
a = 3 b = 2 if a > 2 else 1 #b = 2
参考文档
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