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,这里收集了一些常见的 Pythonic 写法,帮助你养成写优秀代码的习惯。
tmp = a
a = b
b = tmp
a,b = b,a
my_list = []
for i in range(10):
my_list.append(i*2)
my_list = [i*2 for i in range(10)]
print 'one'; print 'two'
if x == 1: print 'one'
if <complex comparison> and <other complex comparison>:
# do something
print 'one'
print 'two'
if x == 1:
print 'one'
cond1 = <complex comparison>
cond2 = <other complex comparison>
if cond1 and cond2:
# do something
for i in range(len(my_list)):
print(i, "-->", my_list[i])
for i,item in enumerate(my_list):
print(i, "-->",item)
a, *rest = [1, 2, 3]
# a = 1, rest = [2, 3]
a, *middle, c = [1, 2, 3, 4]
# a = 1, middle = [2, 3], c = 4
1
letters = ['s', 'p', 'a', 'm']
s=""
for let in letters:
s += let
letters = ['s', 'p', 'a', 'm']
word = ''.join(letters)
if attr == True:
print 'True!'
if attr == None:
print 'attr is None!'
if attr:
print 'attr is truthy!'
if not attr:
print 'attr is falsey!'
if attr is None:
print 'attr is None!'
d = {'hello': 'world'}
if d.has_key('hello'):
print d['hello'] # prints 'world'
else:
print 'default_value'
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']
a = [3, 4, 5]
b = []
for i in a:
if i > 4:
b.append(i)
a = [3, 4, 5]
b = [i for i in a if i > 4]
# Or:
b = filter(lambda x: x > 4, a)
a = [3, 4, 5]
for i in range(len(a)):
a[i] += 3
a = [3, 4, 5]
a = [i + 3 for i in a]
# Or:
a = map(lambda i: i + 3, a)
f = open('file.txt')
a = f.read()
print a
f.close()
with open('file.txt') as f:
for line in f:
print line
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
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)
def make_complex(*args):
x, y = args
return dict(**locals())
def make_complex(x, y):
return {'x': x, 'y': y}
filename = 'foobar.txt'
basename, _, ext = filename.rpartition('.')
if age > 18 and age < 60:
print("young man")
if 18 < age < 60:
print("young man")
>>> False == False == True
False
这个保留意见。随使用习惯就好。
if a > 2:
b = 2
else:
b = 1
#b = 2
a = 3
b = 2 if a > 2 else 1
#b = 2