Question

Possible Duplicate:
Standard way to remove multiple elements from a dataframe

I know in R that if you are searching for a subset of another group or matching based on id you’d use something like

subset(df1, df1$id %in% idNums1)

My question is how to do the opposite or choose items NOT matching a vector of ids.

I tried using ! but get the error message

subset(df1, df1$id !%in% idNums1)

I think my backup is to do sometime like this:

matches <- subset(df1, df1$id %in% idNums1)
nonMatches <- df1[(-matches[,1]),]

but I’m hoping there’s something a bit more efficient.

Answer 1

The expression df1$id %in% idNums1 produces a logical vector. To negate it, you need to negate the whole vector:

!(df1$id %in% idNums1)