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rdataframedelete-row

Delete all rows below specific row in R matching another value on a different data frame

I want to delete all rows in df1 below a specific row. This specific row always matches the first value ("Name") with df2.

df1: | Name | Shape| Date | |:--------|------|------| | 00000 | row |10-2020| | 00001 | row |11-2020| |00002 |row |12-2020| |00003 |row |13-2020| |00004 |row |14-2020|

df2: | Name | Shape| Date | |:-------- | -----|------| |00002 |row |12-2020| |00003 |row |13-2020| |00004 |row |14-2020|

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In this case all rows on df1 below 0002 would be deleted. On df2 rows below 00002 don't necessarily match rows below 00002 on df1. Thanks.

Solution

  • Here is one way to get df1 with rows below the first entry of df2$Name removed via the which function (I just entered "datechar" rather than each date you have in your example since the date is not used).

    df1 <- data.frame("Name"=seq(0,4),
                  "Shape"=rep("row",5),
                  "Date"=rep("datechar",5))
                  
df2 <- data.frame("Name"=seq(2,4),
                  "Shape"=rep("row",3),
                  "Date"=rep("datechar",3))

which(df1$Name == df2$Name[1])

df1[1:(which(df1$Name == df2$Name[1])),]