python - 使用开始日期和结束日期进行左连接

Question

下面前两个表是 cat1和cat2 table 基本上，我希望留下加入cat1与 cat2 ，其中cat1日期介于 cat2 的开始/结束日期之间 最后一个表是结果，我应该如何实现这个结果？

请查找下面的代码 cat1和cat2

import pandas as pd
from datetime import date

cat1=pd.DataFrame({
    "CatID":[1, 2, 3],
    "Date":[date(2019,10,1), date(2019,11,1), date(2019,12,1)]
})

cat2=pd.DataFrame({
    "Interesting":[1, 2, 3],
    "StartDate":[date(2019,10,1), date(2019,11,1), date(2018,10,6)],
    "EndDate":[date(2019,10,30), date(2019,11,30), date(2018,10,6)]
})

Answer 1

最简单的方法..

import pandas as pd
from datetime import date

cat1=pd.DataFrame({"CatID":[1,2,3],
                 "Date":[date(2019,10,1),date(2019,11,1),date(2019,12,1)]})
cat2=pd.DataFrame({"Interesting":[1,2,3],
                 "StartDate":[date(2019,10,1),date(2019,11,1),date(2018,10,6)],
                  "EndDate":[date(2019,10,30),date(2019,11,30),date(2018,10,6)]})

cat3_data = []
for interesting, start, end in cat2.values:
    for d in pd.date_range(start, end, freq='D'):
        cat3_data.append([d.date(), interesting])
cat3 = pd.DataFrame(cat3_data, columns=['Date', 'Interesting'])

result = pd.merge(cat1, cat3, how='left', on='Date')

结果

    CatID   Date    Interesting
0   1   2019-10-01  1.0
1   2   2019-11-01  2.0
2   3   2019-12-01  NaN