Find complement of a data frame (anti - join)
You could also do some type of anti join with data.tables binary join
library(data.table)setkey(setDT(df), heads)[!df1]# heads# 1: row1# 2: row2# 3: row4EDIT: Starting data.table v1.9.6+ we can join data.tables without setting keys while using on
setDT(df)[!df1, on = "heads"]EDIT2: Starting data.table v1.9.8+ fsetdiff was introduced which is basically a variation of the solution above, just over all the column names of the x data.table, e.g. x[!y, on = names(x)]. If all set to FALSE (the default behavior), then only unique rows in x will be returned. For the case of only one column in each data.table the following will be equivalent to the previous solutions
fsetdiff(df, df1, all = TRUE)