遍历字典以创建列表

Question

I have a dictionary, which I want to use to get data from a website and then store a separate value for each key in the dictionary with data coming from a corresponding value. The code works but only returns the data from the last key:value pair in the dictionary, instead of all of them. What am I missing?

import csv
import requests

URL = {'Nov18': 'https://markets.cboe.com/us/futures/market_statistics/historical_data/products/csv/VX/2018-11-21',
       'Dec18': 'https://markets.cboe.com/us/futures/market_statistics/historical_data/products/csv/VX/2018-12-19'}

for tenors, links in URL.items():
    with requests.Session() as s:
        download = s.get(links)

        decoded_content = download.content.decode('utf-8')

        cr = csv.reader(decoded_content.splitlines(), delimiter=',')
        tenors = list(cr)

Answer 1

You have overriden the variable "tenors". Try to define another variable like "date", you will get your results:

import csv
import requests

URL = {'Nov18': 'https://markets.cboe.com/us/futures/market_statistics/historical_data/products/csv/VX/2018-11-21',
         'Dec18': 'https://markets.cboe.com/us/futures/market_statistics/historical_data/products/csv/VX/2018-12-19'}

tenors = []

for date, links in URL.items():
    with requests.Session() as s:
        download = s.get(links)

        decoded_content = download.content.decode('utf-8')

        cr = csv.reader(decoded_content.splitlines(), delimiter=',')
        tenors.append(list(cr))

Answer 2

So a couple things not sure why the variable is called tenor and not date but it should be singular. Link should also be singluar. You can use a dictionary to access by date later on, otherwise the date information is lost.

import csv
import requests

URL = {'Nov18': 'https://markets.cboe.com/us/futures/market_statistics/historical_data/products/csv/VX/2018-11-21',
     'Dec18': 'https://markets.cboe.com/us/futures/market_statistics/historical_data/products/csv/VX/2018-12-19'}

output = {}
for trade_date, link in URL.items():
    with requests.Session() as s:
        download = s.get(link)

        decoded_content = download.content.decode('utf-8')

        cr = csv.reader(decoded_content.splitlines(), delimiter=',')
        output[trade_date]= list(cr)

print(output['Nov18'])
print(output['Dec18'])