Find complement of a data frame (anti - join)

Question

I have two data frames(df and df1). df1 is subset of df. I want to get a data frame which is complement of df1 in df, i.e. return rows of the first data set which are not ma

Answer 1

Late answer, but for another option we can try doing a formal SQL anti join, using the sqldf package:

library(sqldf)
sql <- "SELECT t1.heads
        FROM df t1 LEFT JOIN df1 t2
            ON t1.heads = t2.heads
        WHERE t2.heads IS NULL"
df2 <- sqldf(sql)

The sqldf package can be useful for those problems which are easily phrased using SQL logic, but perhaps less easily phrased using base R or another R package.