Python中集合的不区分大小写比较
问题描述
我有两套(虽然我可以做列表或其他什么):
I have two sets (although I can do lists, or whatever):
a = frozenset(('Today','I','am','fine'))
b = frozenset(('hello','how','are','you','today'))
我想得到:
frozenset(['Today'])
或至少:
frozenset(['today'])
如果我将我假设的所有内容都小写，第二个选项是可行的，但我正在寻找一种更优雅的方式.有可能吗
The second option is doable if I lowercase everything I presume, but I'm looking for a more elegant way. Is it possible to do
a.intersection(b)
以不区分大小写的方式?
in a case-insensitive manner?
Django 中的快捷方式也很好，因为我正在使用该框架.
Shortcuts in Django are also fine since I'm using that framework.
下面的交集方法示例(我无法弄清楚如何在评论中格式化):
Example from intersection method below (I couldn't figure out how to get this formatted in a comment):
print intersection('Today I am fine tomorrow'.split(),
'Hello How a re you TODAY and today and Today and Tomorrow'.split(),
key=str.lower)
[(['tomorrow'], ['Tomorrow']), (['Today'], ['TODAY', 'today', 'Today'])]
解决方案
以下版本适用于任何一对可迭代对象:
Here's version that works for any pair of iterables:
def intersection(iterableA, iterableB, key=lambda x: x):
"""Return the intersection of two iterables with respect to `key` function.
"""
def unify(iterable):
d = {}
for item in iterable:
d.setdefault(key(item), []).append(item)
return d
A, B = unify(iterableA), unify(iterableB)
return [(A[k], B[k]) for k in A if k in B]
例子:
print intersection('Today I am fine'.split(),
'Hello How a re you TODAY'.split(),
key=str.lower)
# -> [(['Today'], ['TODAY'])]
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