遍历列表并删除重复元素时出现循环问题

2022-01-10 00:00:00 python list loops iterator

问题描述

我想遍历一个列表，并删除多次计数的项目，这样它们就不会被 for 循环重复打印.

I want to iterate through a list, and remove the items that count more than once, so they don't get printed repeatedly by the for loop.

但是，列表中仅出现一次的某些项目似乎也受此影响，我不知道为什么.

However, some items appearing only one time in the list seem to get affected too by this, and I can't figure out why.

任何意见将不胜感激.

示例输出:

listy = [2,2,1,3,4,2,1,2,3,4,5]
for i in listy:
  if listy.count(i)>1:
    print i, listy.count(i)
    while i in listy: listy.remove(i)
  else:
    print i, listy.count(i)

输出:

 2 4
 3 2
 1 2

因此完全忽略了 4 和 5.

thus ignoring completely 4 and 5.

解决方案

您不应该在迭代列表时修改它.这个应该可以工作:

You should not modify a list while iterating over it. This one should work:

listy = [2,2,1,3,4,2,1,2,3,4,5]
found = set()
for i in listy:
    if not i in found:
        print i, listy.count(i)
        found.add(i)

结果是:

2 4
1 2
3 2
4 2
5 1

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