dictionary changed size during iteration

最新推荐文章于 2023-03-09 01:00:24 发布

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最新推荐文章于 2023-03-09 01:00:24 发布

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分类专栏： error 文章标签： python error dictionary

本文链接：https://blog.youkuaiyun.com/babaili_/article/details/79441977

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本文探讨了Python中字典迭代删除导致的运行时错误，并提供了两种有效解决方案：通过复制字典或使用键的列表来避免错误。

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今天遇到这种错误 ‘RuntimeError: dictionary changed size during iteration’

字典在迭代时无法改变大小，英语渣轻喷。

>>> test = {'a':1, 'b':2, 'c':3, 'd':4, 'e':5}
>>> for i in test.keys():
	test.pop(i)

	
1
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    for i in test.keys():
RuntimeError: dictionary changed size during iteration

研究了下发现通过复制可以进行删除操作

>>> temp = test.copy()
>>> temp
{'b': 2, 'c': 3, 'd': 4, 'e': 5}
>>> for k in test.keys():
	temp.pop(k)

	
2
3
4
5
>>> temp
{}

或者list化键然后进行删除操作

>>> test = {'a':1, 'b':2, 'c':3, 'd':4, 'e':5}
>>> for k in list(test.keys()):
	test.pop(k)

	
1
2
3
4
5
>>> test
{}
>>>

有个很有趣的现象，直接进行删除操作的时候在报错的同时也删除了迭代的第一个键

>>> test = {'a':1, 'b':2, 'c':3, 'd':4, 'e':5}
>>> for i in test.keys():
	test.pop(i)

	
1
Traceback (most recent call last):
  File "<pyshell#3>", line 1, in <module>
    for i in test.keys():
RuntimeError: dictionary changed size during iteration
>>> test
{'b': 2, 'c': 3, 'd': 4, 'e': 5}
>>> for i in test.keys():
	test.pop(i)

	
2
Traceback (most recent call last):
  File "<pyshell#7>", line 1, in <module>
    for i in test.keys():
RuntimeError: dictionary changed size during iteration
>>> test
{'c': 3, 'd': 4, 'e': 5}
>>> for i in test.keys():
	test.pop(i)

	
3
Traceback (most recent call last):
  File "<pyshell#11>", line 1, in <module>
    for i in test.keys():
RuntimeError: dictionary changed size during iteration
>>> test
{'d': 4, 'e': 5}

道行尚浅，欢迎斧正。