[英]Python list comprehension, with unique items
Is there a way to make a list comprehension in Python that only contains unique items? 有没有办法在Python中仅包含唯一项的列表理解?
My original idea was to use something like this : new_items = [unicode(item) for item in items]
我最初的想法是使用这样的东西:
new_items = [unicode(item) for item in items]
However, I later realized that I needed to omit duplicate items. 但是,后来我意识到我需要省略重复的项目。 So I ended up with this ugly monstrosity :
所以我最终遇到了这个丑陋的怪物:
unique_items = []
for item in items :
unicode_item = unicode(item)
if unicode_item not in unique_items :
unique_items.append(unicode_item)
Now this is far less pretty (and readable) than a simple list comprehension. 现在,这比简单的列表理解要简单得多(而且可读性强)。 So, is there a way to make a list comprehension equivalent to the above code?
因此,有没有办法使列表理解与上述代码等效?
Also order does matter, so I can't just use a set comprehension. 顺序也很重要,所以我不能只使用集合理解。
Well, there is no ordered set, but we can misuse OrderedDict: 好吧,没有有序集,但是我们可以滥用OrderedDict:
from collections import OrderedDict
t = "never gonna give you up"
OrderedDict.fromkeys(t).keys()
Gives: 给出:
['n', 'e', 'v', 'r', ' ', 'g', 'o', 'a', 'i', 'y', 'u', 'p']
您的原始想法具有一定的理解力:
new_items = {unicode(item) for item in items}
I short one liner might be: 我做空一个班轮可能是:
s = "some string"
unique_items = [unicode(ch) for ch in sorted(set(s), key=s.index)]
Make it a helper function, like so. 像这样使它成为一个辅助函数。
def unique_iter(iterable):
seen = set()
for item in iterable:
if item in seen:
continue
seen.add(item)
yield item
for ch in unique_iter("never gonna give you up"):
print ch,
outputs 输出
nevrgoaiyup
nevrgoaiyup
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