记录几个python语法的小技巧。

1. 变换变量

x = 5
y = 6
x, y = y, x
print  x,y

2. 行内if语句

print 'Python' if True else 'Objective-C'

3.连接

l1 = ['python','objective-c']
l2 = ['swift']
l3 = l1 + l2
print l3

4.向下取整

print 5.0//2
print 2**5

5.浮点数的除法

print .3/.1
print .3//.1

6.数值比较

x = 2
if 3 > x < 1:
    print x
if 1 < x > 0:
    print x

7.两个列表同时迭代

l1 = ['python','objective-c']
l2 = ['swift','javascript']
#zip把两个列表组合成一个列表,但是新的列表里面每一个值都是一个tuple
for item1,item2 in zip(l1,l2):
    print item1,item2

8.带索引的迭代

l1 = ['python','objective-c','swift','javascript']
for index,language in enumerate(l1):
print language + ' index is ' + str(index)

9.列表推导

nums = [x for x in range(11)]
    print nums
nums2 = [x for x in nums if x%2 == 0]
    print nums2

10.索引推导

dict = {'name':'shuige','age':'20'}
    print {key:value for value,key in enumerate(dict)}

11.初始化列表

items = [0]*3
    print items

12.列表转换成字符串

l1 = ['python','objective-c','swift','javascript']
    print ','.join(l1)

13.字典取元素

dict = {'name':'shuige','age':'20'}
#如果有值,打印,没有的话,会打印True
name = dict.get('name',True)
    print name

14.切片

x = [x for x in range(11)]
print x[:3]
print x[1::2] #从索引1开始每隔两个
print x[1::3]