如何返回数据帧的json格式？

Question

我有一个dataframe df，并尝试将dataframe转换为json，如下所示：

from flask import Flask
import pandas as pd

app=Flask(__name__)

@app.route('/graph')
def plot():
    df=pd.DataFrame([['madrid', 10], ['venice', 20], ['las vegas', 40], ['brighton', 35]],
                      columns=['city', 'temp'])
    jsondata=df.to_json(orient='records')
    return jsondata

if __name__=='__main__':
    app.run()

o/p如下：

[{"city":"madrid","temp":10},{"city":"venice","temp":20},{"city":"las vegas","temp":40},{"city":"brighton","temp":35}]

如果我使用orient='split' o/p是：

{"columns":["city","temp"],"index":[0,1,2,3],"data":[["madrid",10],["venice",20],["las vegas",40],["brighton",35]]}

我正在寻找一个产出如下：

{
"trace1":[{"city":["madrid",....],"temp":[10,20,...]}]
}

我不知道city和temp可以像上面那样，但是尝试了trace1至少作为return {"trace1":jsondata}，但是这给了我

{
    "trace1": "{\"columns\":[\"city\",\"temp\"],\"index\":[0,1,2,3],\"data\":[[\"madrid\",10],[\"venice\",20],[\"las vegas\",40],[\"brighton\",35]]}"
}

Answer 1

将DataFrame.to_dict与orient='list'一起用于字典，然后转换为json：

import json

jsondata= json.dumps({"trace1":[df.to_dict(orient='list')]})
print (jsondata)

{"trace1": [{"city": ["madrid", "venice", "las vegas", "brighton"],"temp": [10, 20, 40, 35]}]}