Convert Interval Outer Join SQL in R data frame

问题:

I have a same problem in Python before: Convert Interval Outer Join SQL in Python Pandas Dataframe and I would like to do it in R.

I'm converting an Oracle SQL outer interval join into R. Below is the Oracle SQL:

WITH df_interval AS
          (SELECT '1' id,
                     'AAA' interval,
                     1000 begin,
                     2000 end
              FROM DUAL
            UNION ALL
            SELECT '1' id,
                     'BBB' intrvl,
                     2100 begin,
                     3000 end
              FROM DUAL
            UNION ALL
            SELECT '2' id,
                     'CCC' intrvl,
                     3100 begin,
                     4000 end
              FROM DUAL
            UNION ALL
            SELECT '2' id,
                     'DDD' intrvl,
                     4100 begin,
                     5000 end
              FROM DUAL),
      df_point AS
          (SELECT '1' id, 'X1' point, 1100 mid FROM DUAL
            UNION ALL
            SELECT '1' id, 'X2' point, 2050 mid FROM DUAL
            UNION ALL
            SELECT '1' id, 'X3' point, 3200 mid FROM DUAL
            UNION ALL
            SELECT '2' id, 'X4' point, 4200 mid FROM DUAL
            UNION ALL
            SELECT '2' id, 'X5' point, 5500 mid FROM DUAL)
SELECT pt.id,
         point,
         mid,
         interval
  FROM df_interval it RIGHT OUTER JOIN df_point pt ON pt.id = it.id AND pt.mid BETWEEN it.begin AND it.end

I expect the result like this:

  ID point   mid interval
0  1    X1  1100      AAA
1  1    X2  2050      NaN
2  1    X3  3200      NaN
3  2    X4  4200      DDD
4  2    X5  5500      NaN

Appreciate anyone can help me on this?

回答1:

Here is an option using data.table package:

library(data.table)
setDT(df_interval)
setDT(df_point)
df_interval[df_point, on=.(id, begin<=mid, end>=mid),
    .(ID=id, point=i.point, mid=i.mid, interval=x.interval)]

output:

   ID point  mid interval
1:  1    X1 1100      AAA
2:  1    X2 2050     <NA>
3:  1    X3 3200     <NA>
4:  2    X4 4200      DDD
5:  2    X5 5500     <NA>

data:

df_interval <- data.frame(id=c(1,1,2,2), 
    interval=c('AAA','BBB','CCC','DDD'),
    begin=c(1000,2100,3100,4100),
    end=c(2000,3000,4000,5000))
df_point <- data.frame(id=c(1,1,1,2,2),
    point=c('X1','X2','X3','X4','X5'),
    mid=c(1100,2050,3200,4200,5500))