如何解决就地将排列应用于列表的方法？ 按键排序的倒数
| 这是我想做的一个例子spam_list = [\"We\",\"are\",\"the\",\"knights\",\"who\",\"say\",\"Ni\"]
spam_order = [0,1,2,4,5,6,3]
spam_list.magical_sort(spam_order)
print(spam_list)
[\"We\",\"Ni\",\"knights\"]
enumerate
list
spam_list
list.sort()
sorted()
解决方法
您可以尝试：
spam_list = [spam_list[i] for i in spam_order]
key
order = dict(zip(spam_list,spam_order))
spam_list.sort(key=order.get)
Zip
myZip[i]
(list1[i],list2[i])
myZip[i]=(x1,x2)
list1[i]=x1,list2[i]=x2
myZip(spam_list,spam_order).sort()
spam_list
spam_order
#!/usr/bin/python3
class LiveZip(list):
def __init__(self,list1,list2):
self.list1 = list1
self.list2 = list2
def __len__(self):
return len(self.list1)
def __getitem__(self,i):
return (self.list1[i],self.list2[i])
def __setitem__(self,i,tuple):
x1,x2 = tuple
self.list1[i] = x1
self.list2[i] = x2
spam_list = [\"We\",\"are\",\"the\",\"knights\",\"who\",\"say\",\"Ni\"]
spam_order = [0,1,2,4,5,6,3]
#spam_list.magical_sort(spam_order)
proxy = LiveZip(spam_order,spam_list)
#proxy.sort()
#fail --> oops,the internal implementation is not meant to be subclassed! lame
# It turns out that the python [].sort method does NOT work without passing in
# a list to the constructor (i.e. the internal implementation does not use the
# public interface),so you HAVE to implement your own sort if you want to not
# use any extra space. This kind of dumb. But the approach above means you can
# just use any standard textbook in-place sorting algorithm:
def myInPlaceSort(x):
# [replace with in-place textbook sorting algorithm]
myInPlaceSort(proxy)
print(spam_list)
spam_list.sort(key=lambda x:x)
dict.__getitem__
O(N)
[spam_list[i] for i in spam_order]
O(#cycles)
Create a temp variable.
For index i=0...N:
Put x_i into temp,assign NULL to x_i
Swap temp with x_p(i)
Swap temp with x_p(p(i))
...
Swap temp with x_p(..p(i)..),which is x_i
Put a \"do not repeat\" marker on the smallest element you visited larger than i
Whenever you encounter a \"do not repeat\" marker,perform the loop again but
without swapping,moving the marker to the smallest element larger than i
To avoid having to perform the loop again,use a bloom filter
other_spam_list = spam_list
spam_list[:] = [spam_list[i] for i in spam_order]
assert other_spam_list == spam_list
spam_list[:] = (spam_list[i] for i in spam_order)
map(lambda x:spam_list[x],spam_order)
def modifyList(toModify,newList):
toModify[:] = newList
def permuteAndUpdate(toPermute,permutation):
modifyList(toPermute,[toPermute[i] for i in permutation])
permuteAndUpdate(spam_list,spam_order)
print(spam_list)
# [\'We\',\'are\',\'the\',\'Ni\',\'knights\',\'who\',\'say\']
import numpy as np
spam_list = list(np.array(spam_list)[spam_order])
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