Python 反转字典 即key和val互换

代码如下：

encoding=utf-8

print ‘中国’

反转字典 即key和val互换

print ‘—生成器表达式’
dict1={1:2,3:4,6:7,9:10}

def invert_dict(d):
return dict((v,k) for k,v in d.iteritems())

print invert_dict(dict1)

print ‘—列表推导’
def invert_dict2(d):
return dict([(v,k) for k,v in d.iteritems()])

print invert_dict2(dict1)

print ‘—itertools 提高大数据效率’
from itertools import izip

def invert_dict3(d):
return dict(izip(d.itervalues(),d.iterkeys()))

print invert_dict3(dict1)
打印结果如下：
中国
—生成器表达式
{2: 1, 4: 3, 10: 9, 7: 6}
—列表推导
{2: 1, 4: 3, 10: 9, 7: 6}
—itertools 提高大数据效率
{2: 1, 4: 3, 10: 9, 7: 6}