更改列表的副本

Question

我想更改列表的副本而不更改原始列表。我的代码显示副本存储在与原始文件不同的内存地址。但是原始列表随副本一起更改。我做错了什么？

original = ['Humpty', 'Dumpty'],['Jack', 'Sprat']
revised = list(original[:])

# Reverse a name on the revised list.
# Don't alter the original list.
revised[0][0],revised[0][1]=revised[0][1],revised[0][0]

print(f"\nThe original list:\t{original}\nAnd its address:\t{id(original)}")
print(f"\nThe revised list:\t{revised}\nAnd its address:\t{id(revised)}\n")

输出：

The original list:  (['Dumpty', 'Humpty'], ['Jack', 'Sprat'])
And its address:    140586839997408

The revised list:   [['Dumpty', 'Humpty'], ['Jack', 'Sprat']]
And its address:    140586839996848

（我是运行 Python 3.7.4。）

Answer 1

您需要复制内部列表的值。

original = [['Humpty', 'Dumpty'], ['Jack', 'Sprat']]
revised = [ar[:] for ar in original]

# Reverse a name on the revised list.
# Don't alter the original list.
revised[0][0], revised[0][1] = revised[0][1], revised[0][0]

print(f"\nThe original list:\t{original}\nAnd its address:\t{id(original)}")
print(f"\nThe revised list:\t{revised}\nAnd its address:\t{id(revised)}\n")

输出：

The original list:  [['Humpty', 'Dumpty'], ['Jack', 'Sprat']]
And its address:    140210727731136
The revised list:   [['Dumpty', 'Humpty'], ['Jack', 'Sprat']]
And its address:    140210729012672

更改列表的副本

Altering a copy of a list

python

copy

list