Python循环通过url json数据不存储循环结果

Question

尝试从 url 循环遍历 json 结果，然后仅在每 1 分钟自上次结果以来发生更改时才打印结果。一切正常，除了结果只是被重写，所以它总是显示“没有任何改变”。

import time
import sys
import pandas as pd


def main():
    result = []
    print('Checking for available  campsites....')


    url = "https://api.reserve.albertaparks.ca/api/public/campgrounds/67/availability?campingType=campsite" \
          "&arrivalDt=01-Aug-2021&departureDt=13-Sept-2021&unitSize=40&siteType=VEH"
    result = pd.read_json(url)


    df = pd.DataFrame.from_records(result['availability'])
    df = df[df['available'] == True]
    df = df[df['fcfs'] == False]
    df.set_index('date', inplace=True)
    print(df)

res_before = ""
while True:
    res = main()
    if res != res_before:
        print(res)
        res_before = res

    else:
        print("nothing changed")
    # time.sleep(300)

    for i in range(60):
        msg = "Pausing for 1 minute"
        sys.stdout.write("\r{} {} seconds ".format(msg, i))
        time.sleep(1)
        sys.stdout.flush()

             available   fcfs
date                         
01-Aug-2021       True  False
02-Aug-2021       True  False
03-Aug-2021       True  False
04-Aug-2021       True  False
05-Aug-2021       True  False
06-Aug-2021       True  False
07-Aug-2021       True  False
08-Aug-2021       True  False
09-Aug-2021       True  False
10-Aug-2021       True  False
Checking for available  campsites....
None
Pausing for 1 minute 59 seconds Checking for available  campsites....
nothing changed

Answer 1

正如@Praveen 所指出的，您没有从函数中返回任何内容。下面是一段代码，其中进行了一些更改，可以使您的代码正确运行。请参阅注释行以了解所需的更改。

    df.set_index('date', inplace=True)
    print(df)
    return df #>>>> return dataframe

res_before = pd.DataFrame()  #>>>> want to compare dataframes correctly
while True:
    res = main()
    if not res.equals(res_before): #>>>> want to compare dataframes correctly
        print(res)
        res_before = res