如何实现两个有相似元素列表，其中一个删除相似元素——python

alex_py

于 2020-11-26 21:35:34 发布

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文章标签： python

本文链接：https://blog.youkuaiyun.com/alex_py/article/details/110205914

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本文探讨了在Python中如何删除一个列表中与另一个列表相同的元素的问题。通过一个实例展示了错误的尝试和正确的解决方案，强调在使用'for'循环遍历列表时不能直接修改列表。

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如何实现两个有相似元素列表，其中一个删除相似元素——python

#Before the starting
This is my first blog, cause i want to learn english, so i will try to finish every blog all by english. i hope my english will turn to be great!!!
#the following is the main body

here have two lists,
str1 = [1,2,3,4]
str2 = [3,4,5,6]

i want to find the elements that is in str1 but not in str2, at the first, i try the following code:

// An highlighted block
for i in str1:
	if i in str2:
		str1.remove(i)
print(str1)

I hope the result was ‘[1,2]’,however the result is ‘[1,2,3]’. this confused me, and i take so much time to figure out where the problem is.

when we use ‘for’ cycle to traverse every element, we can’t change(add/delete) the list.

here is the right code:

//copy a list of str1
// a blank list
str1_copy =[]
for i in str1:
	str1_copy.append(i)

for i in str1_copy:
	if i in str2:
		str1.remove(i)
print(str1)