打印 Python 字典中的所有唯一值
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Print all Unique Values in a Python Dictionary
提问by dvanaria
I'm struggling with a minor problem in Python (my program is in version 3.2.3 right now).
我在 Python 中遇到了一个小问题（我的程序现在是 3.2.3 版）。
I have a dictionary that looks like this (this is just an example, actually taken from another post here):
我有一本看起来像这样的字典（这只是一个例子，实际上取自这里的另一篇文章）：
[{"abc":"movies"}, {"abc": "sports"}, {"abc": "music"}, {"xyz": "music"}, {"pqr":"music"}, {"pqr":"movies"},{"pqr":"sports"}, {"pqr":"news"}, {"pqr":"sports"}]
I want to simply print() a list of unique values, eliminating duplicates. At the end of this list, I would like to print the number of unique values in the dictionary:
我想简单地打印（）一个唯一值列表，消除重复项。在此列表的末尾，我想打印字典中唯一值的数量：
movies
sports
music
news
4
Any help is appreciated. There are some other posts here I found that were somewhat related, but I don't know Python well enough to apply it to this specific problem.
任何帮助表示赞赏。我发现这里还有一些其他帖子有些相关，但我不太了解 Python，无法将其应用于这个特定问题。
回答by Martijn Pieters
Use a set():
使用set()：
from itertools import chain
unique_values = set(chain.from_iterable(d.values() for d in dictionaries_list))
for value in unique_values:
print(value)
print(len(unique_values))
Use .itervalues()on Python 2 for a little more efficiency. Because you have a listof dictionaries, we need to pull out the values from each of those dictionaries first; I used itertools.chain.from_iterable()with a generator expression to list all values in a sequence:
.itervalues()在 Python 2 上使用会提高一点效率。因为您有一个字典列表，所以我们需要先从每个字典中提取值；我使用itertools.chain.from_iterable()生成器表达式来列出序列中的所有值：
>>> for value in set(chain.from_iterable(d.values() for d in dictionaries_list)):
... print(value)
...
news
sports
movies
music
The alternative is to use nested loops in the generator expression:
另一种方法是在生成器表达式中使用嵌套循环：
>>> for value in set(v for d in dictionaries_list for v in d.values()):
... print(value)
...
news
sports
movies
music
回答by Ashwini Chaudhary
Use sethere as they only contain unique items.
set在这里使用，因为它们只包含独特的项目。
>>> lis = [{"abc":"movies"}, {"abc": "sports"}, {"abc": "music"}, {"xyz": "music"}, {"pqr":"music"}, {"pqr":"movies"},{"pqr":"sports"}, {"pqr":"news"}, {"pqr":"sports"}]
>>> s = set( val for dic in lis for val in dic.values())
>>> s
set(['movies', 'news', 'music', 'sports'])
Loop over this set to get the expected output:
循环这个集合以获得预期的输出：
for x in s:
print x
print len(s) #print the length of set after the for-loop
...
movies
news
music
sports
4
This line s = set( val for dic in lis for val in dic.values())is roughly equivalent to:
这一行s = set( val for dic in lis for val in dic.values())大致相当于：
s = set()
for dic in lis:
for val in dic.values():
s.add(val)
回答by Bala Subrahmanyam Balli
dict = {'511':'Vishnu','512':'Vishnu','513':'Ram','514':'Ram','515':'sita'}
list =[] # create empty list
for val in dict.values():
if val in list:
continue
else:
list.append(val)
print list
回答by Joe Silverstein
You can exploit the properties of setfor this purpose; each element is unique and duplicates will be ignored.
您可以set为此目的利用 的属性；每个元素都是唯一的，重复项将被忽略。
uniqueValues = set(myDict.values())
By using setin this way, duplicate elements returned from .values()will be discarded. You can then print them as follows:
通过set这种方式使用，返回的重复元素.values()将被丢弃。然后，您可以按如下方式打印它们：
for value in uniqueValues:
print(value)
print(len(uniqueValues))
