在字典中附加一个 int 键

Question

我正在尝试根据以下列表创建字典：

link_i = [1, 1, 3, 3, 3, 4, 4, 5, 5, 6]
link_j = [2, 3, 1, 2, 5, 5, 6, 6, 4, 4]

link_i = [1, 1, 3, 3, 3, 4, 4, 5, 5, 6]
link_j = [2, 3, 1, 2, 5, 5, 6, 6, 4, 4]
nodes = [1, 2, 3, 4, 5, 6]

# Creating a dictionary containing nodes and their incoming links:
out_dict =  {}
for i in nodes:
    for j in range(0,len(link_i)):
        if (link_i[j] == i):
            if i not in out_dict:
                out_dict[i] = link_j[j]
            elif i in out_dict:
               out_dict[i].append(link_j[j])

但是，我无法附加密钥，因为它的类型是 int。我收到错误：

line 21, in <module>
    out_dict[i].append(link_j[j])

AttributeError: 'int' object has no attribute 'append'

我试图让输出为：

{1: [2, 3], 3: [1, 2, 5], 4: [5, 6], 5: [6, 4], 6: [4]}

Answer 1

您需要更改：

if i not in out_dict:
    out_dict[i] = link_j[j]

至

if i not in out_dict:
    out_dict[i] = [link_j[j]]

这是因为在您第一次将键“i”添加到 out_dict 之后，您将为其分配一个 int 类型的值。为了能够添加到此，稍后，它需要是可变数据类型，例如具有属性追加的列表。这并不能解决您所有的问题，因为即使进行了此更改，您仍然无法获得所需的输出，但它可以让您进一步调试。

Answer 2

为了保持代码简单，您可以使用字典 comprehension 并将每个节点的默认值设置为空列表。这样你就不需要检查节点是否已经是字典的一部分，你可以只附加链接。

link_i = [1, 1, 3, 3, 3, 4, 4, 5, 5, 6]
link_j = [2, 3, 1, 2, 5, 5, 6, 6, 4, 4]
nodes = [1, 2, 3, 4, 5, 6]

# Creating a dictionary containing nodes and their incoming links:
# fill the dict with empty lists for each node
out_dict =  {node: [] for node in nodes}
for i in nodes:
    for j in range(0,len(link_i)):
        if (link_i[j] == i):
            # append link to the list for the node
            out_dict[i].append(link_j[j])

输出如下所示：

{1: [2, 3], 2: [], 3: [1, 2, 5], 4: [5, 6], 5: [6, 4], 6: [4]}

在字典中附加一个 int 键

Appending an int key in a dictionary

dictionary

integer

list

python-3.x