Python 添加到列表中的整数
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Add to integers in a list
提问by fangus
I have a list of integers and I was wondering if it would be possible to add to individual integers in this list.
我有一个整数列表，我想知道是否可以添加到此列表中的单个整数。
采纳答案by John La Rooy
Here is an example where the things to add come from a dictionary
这是一个示例，其中要添加的内容来自字典
>>> L = [0, 0, 0, 0]
>>> things_to_add = ({'idx':1, 'amount': 1}, {'idx': 2, 'amount': 1})
>>> for item in things_to_add:
... L[item['idx']] += item['amount']
...
>>> L
[0, 1, 1, 0]
Here is an example adding elements from another list
这是从另一个列表添加元素的示例
>>> L = [0, 0, 0, 0]
>>> things_to_add = [0, 1, 1, 0]
>>> for idx, amount in enumerate(things_to_add):
... L[idx] += amount
...
>>> L
[0, 1, 1, 0]
You could also achieve the above with a list comprehension and zip
您还可以通过列表理解和 zip 来实现上述目标
L[:] = [sum(i) for i in zip(L, things_to_add)]
Here is an example adding from a list of tuples
这是从元组列表中添加的示例
>>> things_to_add = [(1, 1), (2, 1)]
>>> for idx, amount in things_to_add:
... L[idx] += amount
...
>>> L
[0, 1, 1, 0]
回答by Tim Pietzcker
Yes, it is possible since lists are mutable.
是的，这是可能的，因为列表是可变的。
Look at the built-in enumerate()function to get an idea how to iterate over the list and find each entry's index (which you can then use to assign to the specific list item).
查看内置enumerate()函数以了解如何遍历列表并找到每个条目的索引（然后您可以使用该索引分配给特定的列表项）。
回答by The Communist Duck
fooList = [1,3,348,2]
fooList.append(3)
fooList.append(2734)
print(fooList) # [1,3,348,2,3,2734]
回答by Gordon Gustafson
You can append to the end of a list:
您可以附加到列表的末尾：
foo = [1, 2, 3, 4, 5]
foo.append(4)
foo.append([8,7])
print(foo) # [1, 2, 3, 4, 5, 4, [8, 7]]
You can edit items in the list like this:
您可以像这样编辑列表中的项目：
foo = [1, 2, 3, 4, 5]
foo[3] = foo[3] + 4
print(foo) # [1, 2, 3, 8, 5]
Insert integers into the middle of a list:
在列表中间插入整数：
x = [2, 5, 10]
x.insert(2, 77)
print(x) # [2, 5, 77, 10]
回答by devDeejay
If you try appending the number like, say
listName.append(4), this will append 4at last.
But if you are trying to take <int>and then append it as, num = 4followed by listName.append(num), this will give you an error as 'num' is of <int> typeand listName is of type <list>. So do type cast int(num)before appending it.
如果您尝试附加数字，例如
listName.append(4)，这将4最后附加。但是，如果您尝试采用<int>然后将其附加为 as，num = 4后跟listName.append(num)，这会给您带来错误 as'num' is of <int> type和listName is of type <list>。所以int(num)在追加之前做类型转换。
