从列表中替换重复的项目,同时保持第一次出现 [英] Replace duplicate items from list while keeping the first occurrence
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问题描述
我有一个列表lst = [1,1,1,2,2,2,2,3,3,3,3,3,4,4,4,4,4,4,4,4,4]
我期待以下输出:
out = [1,"","",2,"","","",3,"","","","",4,"","","","","","","",""]
我想保留该项目的第一个匹配项,并用空字符串替换同一项目的所有其他匹配项.
I want to keep the first occurrence of the item and replace all other occurrences of the same item with empty strings.
我尝试了以下方法.
`def splrep(lst):
from collections import Counter
C = Counter(lst)
flst = [ [k,]*v for k,v in C.items()]
nl = []
for i in flst:
nl1 = []
for j,k in enumerate(i):
nl1.append(j)
nl.append(nl1)
ng = list(zip(flst, nl))
for i,j in ng:
j.pop(0)
for i,j in ng:
for k in j:
i[k] = ''
final = [i for [i,j] in ng]
fin = [i for j in final for i in j]
return fin`
但是我正在寻找一些更简单或更好的方法.
But I'm looking for some simpler or better approaches.
推荐答案
Use itertools.groupby
, quite appropriate for grouping consecutively duplicate values.
from itertools import groupby
[v for k, g in groupby(lst) for v in [k] + [""] * (len(list(g))-1)]
# [1, '', '', 2, '', '', '', 3, '', '', '', '', 4, '', '', '', '', '', '', '', '']
如果您的列表值不是连续的,则可以先对它们进行排序.
If your list values are not consecutive, you may sort them first.
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