Created
August 25, 2013 04:39
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Python Index, IndexBag, Multidex
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| In [1]: import index | |
| In [2]: i = index.Multidex(unique_keys=('pk',), common_keys=('name',)) | |
| In [3]: class Person(object): | |
| def __init__(self, name): | |
| global last_pk | |
| self.pk = last_pk | |
| last_pk += 1 | |
| self.name = name | |
| ...: | |
| In [4]: last_pk = 1 | |
| In [5]: people = [Person('Alice'), Person('Bob'), Person('Christina'), Person('Christina')] | |
| In [6]: i.merge(people) | |
| In [7]: i.at('pk', 1) | |
| Out[7]: <__main__.Person at 0x1017c2490> | |
| In [8]: i.at('name', 'Christina') | |
| Out[8]: {<__main__.Person at 0x1017c26d0>, <__main__.Person at 0x1017c2710>} |
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| import collections | |
| import operator | |
| class IndexBase(object): | |
| def __init__(self, key, initial=None): | |
| if isinstance(key, basestring): | |
| self.key = operator.attrgetter(key) | |
| elif isinstance(key, int): | |
| self.key = operator.itemgetter(key) | |
| else: | |
| raise ValueError('key must be a basestring or int.') | |
| if initial: | |
| self.merge(initial) | |
| def merge(self, items): | |
| raise NotImplementedError | |
| def add(self, item): | |
| self.merge([item]) | |
| def umerge(self, items): | |
| raise NotImplementedError | |
| def remove(self, item): | |
| self.unmerge([item]) | |
| class Index(IndexBase, dict): | |
| def __init__(self, *args, **kwargs): | |
| super(Index, self).__init__(*args, **kwargs) | |
| def merge(self, items): | |
| for item in items: | |
| self[self.key(item)] = item | |
| def unmerge(self, items): | |
| for item in items: | |
| k = self.key(item) | |
| if self.get(k) == item: | |
| del self[k] | |
| class IndexBag(IndexBase, collections.defaultdict): | |
| def __init__(self, *args, **kwargs): | |
| super(IndexBase, self).__init__(set) | |
| super(IndexBag, self).__init__(*args, **kwargs) | |
| def merge(self, items): | |
| for item in items: | |
| self[self.key(item)].add(item) | |
| def unmerge(self, items): | |
| for item in items: | |
| try: | |
| self[self.key(item)].remove(item) | |
| except KeyError: | |
| continue | |
| class Multidex(object): | |
| def __init__(self, unique_keys=None, common_keys=None, initial=None): | |
| self._indicies = {} | |
| unique_keys = unique_keys or [] | |
| common_keys = common_keys or [] | |
| for key in unique_keys: | |
| self._indicies[key] = Index(key, initial=initial) | |
| for key in common_keys: | |
| self._indicies[key] = IndexBag(key, initial=initial) | |
| def by_key(self, key): | |
| return self._indicies[key] | |
| def at(self, key, val): | |
| return self.by_key(key)[val] | |
| def merge(self, items): | |
| for index in self._indicies.itervalues(): | |
| index.merge(items) | |
| def unmerge(self, items): | |
| for index in self._indices.itervalues(): | |
| index.unmerge(items) | |
| def add(self, item): | |
| self.merge([item]) | |
| def remove(self, item): | |
| self.unmerge([item]) |
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