迭代从特定键开始的有序dict项

一个适用于Python 2和3的解决方案,使用 itertools.dropwhile() :

from __future__ import print_function

from collections import OrderedDict
from itertools import dropwhile

d = OrderedDict(zip(['a', 'b', 'c', 'd'], range(4)))

for k, v in dropwhile(lambda x: x[0] != 'b', d.items()):
    print(k, v)

输出:

b 1
c 2
d 3

Python 2,避免创建键值列表 .items() ::

for k, v in dropwhile(lambda x: x[0] != 'b', d.iteritems()):
    print(k, v)

时间安排

%timeit
for each in d.items()[d.keys().index('b'):]:
    pass
The slowest run took 5.18 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 3.27 µs per loop

%%timeit
for each in islice(d.iteritems(), d.keys().index('b'), None):
    pass
The slowest run took 5.23 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 3.05 µs per loop

%%timeit
for k, v in dropwhile(lambda x: x[0] != 'b', d.iteritems()):
    pass
The slowest run took 4.92 times longer than the fastest. This could mean that an intermediate result is being cached.
100000 loops, best of 3: 2.23 µs per loop

您可以通过查找 b 通过使用 items() 把你需要的地方切掉。代替 d.keys().index('b') 如果你有自己的方式知道你想从哪里开始。

from collections import OrderedDict

d = OrderedDict(zip(['a', 'b', 'c', 'd'], range(4)))

for each in d.items()[d.keys().index('b'):]:
    print(each)

使用 项目() 允许您像往常一样关闭键和值。

在我看来,如果您不想索引元组列表,这是一个选项:

from collections import OrderedDict
from itertools import islice

d = OrderedDict(zip(['a', 'b', 'c', 'd'], range(4)))

for each in islice(d.iteritems(), d.keys().index('b'), None):
    print(each)

这样行吗?

for x in list(a.keys())[a.index(my_key):]:
    print(a[x])

哪里 my_key 是要从中开始的关键点