将 Pandas Dataframe 转换为 JSON 格式：如何分组

Question

我有一个 Pandas 数据框：

     nodes        x      y        z
0        1   0.0000  0.000   0.0000
1        2   0.0000  9.144   0.0000
2        3  19.5072  0.000   0.0000
3        4  19.5072  9.144   0.0000
4        5   9.7536  0.000   0.0000
..     ...      ...    ...      ...
175    176  19.5072  9.144  27.7368
176    177  19.5072  9.144  25.7556
177    178  19.5072  9.144  21.7932
178    179  19.5072  9.144  19.8120
179    180  19.5072  9.144  17.8308

转换为 JSON：

{
    "nodes": {
        "1": {
            "x": 0,
            "y": 0,
            "z": 0
        },
        "2": {
            "x": 0,
            "y": 9.144,
            "z": 0
        },
        "3": {
            "x": 19.5072,
            "y": 0,
            "z": 0
        },
        "4": {
            "x": 19.5072,
            "y": 9.144,
            "z": 0
        },
        "5": {
            "x": 9.7536,
            "y": 0,
            "z": 0
        },
    },
}

我刚开始使用python。谷歌之后，我尝试了：

out = df.to_json(orient = 'records')
print(json.dumps(json.loads(out), indent=4))

结果：

{
    "nodes": 1,
    "x": 0.0,
    "y": 0.0,
    "z": 0.0
},
{
    "nodes": 2,
    "x": 0.0,
    "y": 9.144,
    "z": 0.0
},
{
    "nodes": 3,
    "x": 19.5072,
    "y": 0.0,
    "z": 0.0
},

请帮忙。谢谢。

Answer 1

您可以利用groupby 函数来实现您想要的输出：

out = {'nodes': df.groupby('nodes').last().to_dict(orient='index')}
print(json.dumps(out, indent=4))

结果：

{
    "nodes": {
        "1": {
            "x": 0.0,
            "y": 0.0,
            "z": 0.0
        },
        "2": {
            "x": 0.0,
            "y": 9.144,
            "z": 0.0
        },
        "3": {
            "x": 19.5072,
            "y": 0.0,
            "z": 0.0
        },
        "4": {
            "x": 19.5072,
            "y": 9.144,
            "z": 0.0
        },
        "5": {
            "x": 9.7536,
            "y": 0.0,
            "z": 0.0
        }
    }
}