列出插入新项目时的行为 [英] List Behavior when inserting new items
问题描述
我想在项目列表中添加一个元素，但是我想
将它添加到大于当前大小的特定索引处：
list = [1,2,3]
list.insert（10,4）
我想要什么看来是这样的：
[1,2,3 ,,,,,, 4]
但是我看到了：
[1,2,3,4]
有没有办法轻易产生这种行为？
谢谢，
画了
I''m looking to add an element to list of items, however I''d like to
add it at a specific index greater than the current size:
list = [1,2,3]
list.insert(10,4)
What I''d like to see is something like:
[1,2,3,,,,,,4]
However I see:
[1,2,3,4]
Is there any way to produce this kind of behavior easily?
Thanks,
Drew
推荐答案
Drew schrieb：
Drew schrieb:
我想在项目列表中添加一个元素，但是我想在一个大于当前大小的特定索引处添加
：
list = [1,2,3]
list.insert（10,4）
什么我希望看到类似的东西：
[1,2,3 ,,,,,, 4]
但是我明白了：
[1,2,3,4]
有吗任何方式容易产生这种行为？
I''m looking to add an element to list of items, however I''d like to
add it at a specific index greater than the current size:
list = [1,2,3]
list.insert(10,4)
What I''d like to see is something like:
[1,2,3,,,,,,4]
However I see:
[1,2,3,4]
Is there any way to produce this kind of behavior easily?
使用字典？
如果知道列表最终会有多大，那每个
位置已填充，您也可以使用range（n）创建列表。
您的实际用例是什么？
diez
Use a dictionary?
If you know how large the list eventually will be, and that each
position is filled, you can also use range(n) to create a list.
What is your actual usecase?
diez
你的实际用例是什么？
What is your actual usecase?
>
diez
>
diez
问题是我不喜欢不知道列表最终会持续多长时间。
基本上我正在尝试使用2D列表来保存我将最终打印到屏幕上的行b
。列表中的空白元素将以空格打印。
我想每次添加一个元素，我都可以找到
列表大小和所需索引之间的差异，并且
填写&b之间的范围。 "价值，但我只想
看看语言是否有更自然的方式。
谢谢，
德鲁
The issue is that I don''t know how long the list will eventually be.
Essentially I''m trying to use a 2D list to hold lines that I will
eventually print to the screen. Blank elements in the list will be
printed as spaces. I suppose every time I add an element, I could find
the difference between the size of the list and the desired index and
fill in the range between with " " values, however I just wanted to
see if there was a more natural way in the language.
Thanks,
Drew
1月29日下午7:57，Drew < olso ... @ gmail.comwrote：
On Jan 29, 7:57 pm, "Drew" <olso...@gmail.comwrote:
我想在项目列表中添加一个元素，但是我想
将其添加到大于当前大小的特定索引：
list = [1,2,3]
list.insert （10,4）
我想看到的是：
[1,2,3 ,,, ,,, 4]
但是我明白了：
[1,2,3,4]
有没有办法轻易产生这种行为？
谢谢，
画了
I''m looking to add an element to list of items, however I''d like to
add it at a specific index greater than the current size:
list = [1,2,3]
list.insert(10,4)
What I''d like to see is something like:
[1,2,3,,,,,,4]
However I see:
[1,2,3,4]
Is there any way to produce this kind of behavior easily?
Thanks,
Drew
您可以编写自己的类来模拟具有所需
行为的列表，例如：
py> class llist（object）：
py def __init __（self，arg = []）：
py self .__ list = arg
py def __setitem __（self，key，值）：
py length = len（self .__ list）
py if length< key：
py for i in range（length，key +1）：
py self .__ list.append（None）
py self .__ list [key] = value
py def __str __（self）：
py return str（self .__ list）
py>
py> x = llist（）
py> x [10] = 1
py>打印x
[无，无，无，无，无，无，无，无，无，无，1]
其他方法添加到llist类请参阅 http://docs.python.org/
ref / sequence-types.html
You could write your own class mimicing a list with your desired
behaviour, something like:
py>class llist(object):
py def __init__(self, arg = []):
py self.__list = arg
py def __setitem__(self, key, value):
py length = len(self.__list)
py if length < key:
py for i in range(length, key +1):
py self.__list.append(None)
py self.__list[key] = value
py def __str__(self):
py return str(self.__list)
py>
py>x = llist()
py>x[10] = 1
py>print x
[None, None, None, None, None, None, None, None, None, None, 1]
for other methods to add to the llist class see http://docs.python.org/
ref/sequence-types.html
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