如何使字典列表中的值唯一? [英] How to make values in list of dictionary unique?
问题描述
我有一个 Python 字典列表，如下所示:
d = [{feature_a:1, feature_b:'Jul', feature_c:100}, {feature_a:2, feature_b:'Jul', feature_c:150}, {feature_a:1, feature_b:'Mar', feature_c:110}, ...]我想要实现的是保持 feature_a、_b 和 _c 的唯一性.
例如，如果我们有 3 个条目，它们具有相同的 feature_a 和 _b，但是 feature_c 有 3 个不同的值 100、100、150，那么操作后应该是100和150.
我怎样才能做到这一点?
==================================================================更新:
好的，感谢 Anand 的出色回答，它完美运行.不过，我还有一个问题.
假设我们有一个新的 feature_d 并且字典看起来像:
d = [{feature_a:1, feature_b:'Jul', feature_c:100, feature_d:'A'}, {feature_a:2, feature_b:'Jul', feature_c:150, feature_d: 'B'}, {feature_a:1, feature_b:'Mar', feature_c:110, feature_d:'F'}, ...]而且我只想对 feature_a、_b 和 _c 进行重复数据删除，而将 feature_d 排除在外.我怎样才能做到这一点?
非常感谢.
如果初始d列表的顺序不重要，可以取.items() 每个字典并将其转换为 frozenset() ，这是可散列的，然后您可以将整个内容转换为 set() 或 frozenset() ，然后转换每个 frozenset() 回到字典.示例 -
uniq_d = list(map(dict,frozenset(frozenset(i.items()) for i in d)))sets() 不允许重复元素.虽然你最终会失去列表的顺序.对于 Python 2.x ，不需要 list(...)，因为 map() 返回一个列表.
示例/演示 -
<预><代码>>>>导入打印>>>pprint.pprint(d)[{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 100},{'feature_a':2，'feature_b':'Jul'，'feature_c':150}，{'feature_a': 1, 'feature_b': 'Mar', 'feature_c': 110},{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 100},{'feature_a':1，'feature_b':'Jul'，'feature_c':150}]>>>uniq_d = list(map(dict,frozenset(frozenset(i.items()) for i in d)))>>>pprint.pprint(uniq_d)[{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 100},{'feature_a':1，'feature_b':'Jul'，'feature_c':150}，{'feature_a': 1, 'feature_b': 'Mar', 'feature_c': 110},{'feature_a':2，'feature_b':'Jul'，'feature_c':150}]对于新要求 -
<块引用>但是，如果我有另一个 feature_d 但我只想删除 feature_a、_b 和 _c 怎么办
如果两个条目具有相同的 feature_a、_b 和 _c，无论在 feature_d 中是什么，它们都被认为是相同的和重复的
一个简单的方法是使用一个集合和一个新列表，只将您需要的功能添加到集合中，并仅使用您需要的功能进行检查.示例 -
seen_set = set()new_d = []对于 d 中的 i:如果 tuple([i['feature_a'],i['feature_b'],i['feature_c']]) 不在 see_set 中:new_d.append(i)see_set.add(tuple([i['feature_a'],i['feature_b'],i['feature_c']]))示例/演示 -
<预><代码>>>>d = [{'feature_a':1, 'feature_b':'Jul', 'feature_c':100, 'feature_d':'A'},... {'feature_a':2, 'feature_b':'Jul', 'feature_c':150, 'feature_d': 'B'},... {'feature_a':1, 'feature_b':'Mar', 'feature_c':110, 'feature_d':'F'},... {'feature_a':1, 'feature_b':'Mar', 'feature_c':110, 'feature_d':'G'}]>>>see_set = set()>>>new_d = []>>>对于 d 中的 i:...如果 tuple([i['feature_a'],i['feature_b'],i['feature_c']]) 不在 see_set 中:... new_d.append(i)... see_set.add(tuple([i['feature_a'],i['feature_b'],i['feature_c']]))...>>>pprint.pprint(new_d)[{'feature_a':1，'feature_b':'Jul'，'feature_c':100，'feature_d':'A'}，{'feature_a':2，'feature_b':'Jul'，'feature_c':150，'feature_d':'B'}，{'feature_a':1，'feature_b':'Mar'，'feature_c':110，'feature_d':'F'}]I have a list of dictionaries in Python, which looks like following:
d = [{feature_a:1, feature_b:'Jul', feature_c:100}, {feature_a:2, feature_b:'Jul', feature_c:150}, {feature_a:1, feature_b:'Mar', feature_c:110}, ...]
What I want to achieve is that to keep the feature_a, _b and _c unique.
For example, if we have 3 entries which have the same feature_a and _b, but have 3 different values of feature_c 100, 100, 150, then after the operation, it should be 100 and 150.
How can I achieve this?
================================================================ UPDATE：
OK, Thanks for Anand's excellent answer, it works perfectly. However, I have a further question.
Suppose we have a new feature_d and the dictionary looks like:
d = [{feature_a:1, feature_b:'Jul', feature_c:100, feature_d:'A'}, {feature_a:2, feature_b:'Jul', feature_c:150, feature_d: 'B'}, {feature_a:1, feature_b:'Mar', feature_c:110, feature_d:'F'}, ...]
and I only want to deduplicate feature_a, _b and _c, but leave feature_d out. How can I achieve this?
Many thanks.
If the order of the initial d list is not important , you can take the .items() of each dictionary and convert it into a frozenset() , which is hashable, and then you can convert the whole thing to a set() or frozenset() , and then convert each frozenset() back to dictionary. Example -
uniq_d = list(map(dict, frozenset(frozenset(i.items()) for i in d)))
sets() do not allow duplicate elements. Though you would end up losing the order of the list. For Python 2.x , the list(...) is not needed, as map() returns a list.
Example/Demo -
>>> import pprint
>>> pprint.pprint(d)
[{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 100},
{'feature_a': 2, 'feature_b': 'Jul', 'feature_c': 150},
{'feature_a': 1, 'feature_b': 'Mar', 'feature_c': 110},
{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 100},
{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 150}]
>>> uniq_d = list(map(dict, frozenset(frozenset(i.items()) for i in d)))
>>> pprint.pprint(uniq_d)
[{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 100},
{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 150},
{'feature_a': 1, 'feature_b': 'Mar', 'feature_c': 110},
{'feature_a': 2, 'feature_b': 'Jul', 'feature_c': 150}]
For the new requirement -
However, what if that I have another feature_d but I only want to dedup feature_a, _b and _c
If two entries which have same feature_a, _b and _c, they are considered the same and duplicated, no matter what is in feature_d
A simple way to do this is to use a set and a new list, add only the features you need to the set, and check using only the features you need. Example -
seen_set = set()
new_d = []
for i in d:
if tuple([i['feature_a'],i['feature_b'],i['feature_c']]) not in seen_set:
new_d.append(i)
seen_set.add(tuple([i['feature_a'],i['feature_b'],i['feature_c']]))
Example/Demo -
>>> d = [{'feature_a':1, 'feature_b':'Jul', 'feature_c':100, 'feature_d':'A'},
... {'feature_a':2, 'feature_b':'Jul', 'feature_c':150, 'feature_d': 'B'},
... {'feature_a':1, 'feature_b':'Mar', 'feature_c':110, 'feature_d':'F'},
... {'feature_a':1, 'feature_b':'Mar', 'feature_c':110, 'feature_d':'G'}]
>>> seen_set = set()
>>> new_d = []
>>> for i in d:
... if tuple([i['feature_a'],i['feature_b'],i['feature_c']]) not in seen_set:
... new_d.append(i)
... seen_set.add(tuple([i['feature_a'],i['feature_b'],i['feature_c']]))
...
>>> pprint.pprint(new_d)
[{'feature_a': 1, 'feature_b': 'Jul', 'feature_c': 100, 'feature_d': 'A'},
{'feature_a': 2, 'feature_b': 'Jul', 'feature_c': 150, 'feature_d': 'B'},
{'feature_a': 1, 'feature_b': 'Mar', 'feature_c': 110, 'feature_d': 'F'}]
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