pandas - '<' not supported between instances of ' 日期时间.日期' 和 'str'

Question

我收到一个类型错误:

TypeError: '<' not supported between instances of 'datetime.date' and 'str'`

运行以下代码时:

import requests
import re
import json
import pandas as pd

def retrieve_quotes_historical(stock_code):
    quotes = []
    url = 'https://finance.yahoo.com/quote/%s/history?p=%s' % (stock_code, stock_code)
    r = requests.get(url)
    m = re.findall('"HistoricalPriceStore":{"prices":(.*?), "isPending"', r.text)
    if m:
        quotes = json.loads(m[0])
        quotes = quotes[::-1]
    return  [item for item in quotes if not 'type' in item]

quotes = retrieve_quotes_historical('INTC')
df = pd.DataFrame(quotes)

s = pd.Series(pd.to_datetime(df.date, unit='s'))
df.date = s.dt.date
df = df.set_index('date')

这段代码运行得很顺利，但是当我尝试运行这段代码时:

df['2017-07-07':'2017-07-10']

我收到类型错误。

我该如何解决这个问题？

Answer 1

问题是，当索引的类型为 datetime.date 时，您想使用字符串 '2017-07-07' 进行切片。您的切片也应该是这种类型。

您可以通过定义开始日期和结束日期来实现此目的，如下所示:

import pandas as pd

startdate = pd.to_datetime("2017-7-7").date()
enddate = pd.to_datetime("2017-7-10").date()
df.loc[startdate:enddate]

startdate 和 enddate 现在的类型为 datetime.date 并且您的切片将起作用:

            adjclose    close        high        low            open        volume
date
2017-07-07    33.205006    33.880001    34.119999    33.700001    33.700001    18304500
2017-07-10    32.979588    33.650002    33.740002    33.230000    33.250000    29918400

也可以在没有 pandas 的情况下创建 datetime.date 类型:

import datetime

startdate = datetime.datetime.strptime('2017-07-07', "%Y-%m-%d").date()
enddate = datetime.datetime.strptime('2017-07-10', "%Y-%m-%d").date()