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[英]Compare two lists of lists in Python and find the difference between lists with the same indices
[英]python compare difference between two lists
我有兩個這樣的清單:
newList = (
(1546, 'John'),
(8794, 'Michael'),
(892416, 'Dave'),
(456789, 'Lucy'),
)
oldList = (
(1546, 'John'),
(8794, 'Michael'),
(892416, 'Dave'),
(246456, 'Alexander')
)
我想有一個比較兩個列表的函數。 就像這樣:
def compare(new, old):
print('Alexander is not anymore in the new list !')
print('Lucy is new !')
return newList
我想與每個人的ID進行比較。
編輯:結果將是我的功能比較。 它打印出差異。 我不知道怎么開始
您可以將列表轉換成集合並進行區別
n = set(l[1] for l in newList)
o = set(l[1] for l in oldList)
print n - o # set(['Lucy'])
print o - n # set(['Alexander'])
編輯:我寫這是在我不了解集合之前。 現在,我將建議使用下面給出的集合的解決方案。
一種解決方案:
removed = [o for o in old if o[0] not in [n[0] for n in new]]
added = [n for n in new if n[0] not in [o[0] for o in old]]
或者,如果您將數據顯示為字典:
old = dict(old) # if you do go for this approach be sure to build these
new = dict(new) # variables as dictionaries, not convert them each time
removed = {k:old[k] for k in old.keys() - new.keys()}
added = {k:new[k] for k in new.keys() - old.keys()}
兩者都變成了函數,以ys
返回項目,但沒有以xs
返回項目:
def tuple_list_additions(xs,ys):
return [y for y in ys if y[0] not in [x[0] for x in xs]]
def dict_additions(xs,ys):
return {k:ys[k] for k in ys.keys() - xs.keys()}
您可以使用set
:
def compare(old, new):
oldSet = set(old)
newSet = set(new)
removedElements = oldSet - newSet
newElements = newSet - oldSet
for element in removedElements:
print(element[1] + " is not anymore in the new list!")
for element in newElements:
print(element[1] + " is new!")
它是一種比較整個元素(id,name)的方法,因此,如果您只想比較id,則應該進行一些修改(例如使用dicts)。
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