python中移除列表元素所遇到的坑

题目：移除列表中除字符串外的元素

方法1：移除时考虑元素位置的改变
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#修改前
list_3 = ["abc","2",2,4.4,"4.4","",99,"abcd",666,"777","444.4",444.4]
[list_3.remove(i) for i in list_3 if 'str' not in str(type(i))]  
print(list_3)  #['abc', '2', 4.4, '4.4', '', 'abcd', '777', '444.4']
#分析原因：由于移除列表中的元素，导致列表中元素的位置发生改变，从而引起有的元素未按题意中移除
#修改后
list_3 = ["abc","2",2,4.4,"4.4","",99,"abcd",666,"777","444.4",444.4]
i = 0
while i < len(list_3):
    if not isinstance(list_3[i],str):
        list_3.remove(list_3[i])
        i = i
    else:
        i = i+1
print(list_3)  #['abc', '2', '4.4', '', 'abcd', '777', '444.4']

方法2：用另一个列表接受要移除的数据，然后在遍历移除

list_3 = ["abc","2",2,4.4,"4.4","",99,"abcd",666,"777","444.4",444.4]
remove_list = [k for k in list_3 if not isinstance(k,str)]
result_list = [list_3.remove(j) for j in remove_list]
print(list_3)  #['abc', '2', '4.4', '', 'abcd', '777', '444.4']

#同理，遍历字典是不能移除字典中的键值对，因为元素位置发生了改变

纸上得来终觉浅，绝知此事要躬行。

本文地址：https://blog.csdn.net/weixin_43509698/article/details/107305072