Using grep in R to delete rows from a data.frame

Question

I have a dataframe such as this one:

    d <- data.frame(cbind(x=1, y=1:10,    z=c(\"apple\",\"pear\",\"banana\",\"A\",\"B\",\"C\",\"D\",\"E\",\"F\",\"G\"         


        

Answer 1

Here's your problem:

> grep("K",c("apple","pear","banana","A","B","C","D","E","F","G"))
integer(0)

Try grepl() instead:

d[!grepl("K",d$z),]

This works because the negated logical vector has an entry for every row:

> grepl("K",d$z)
 [1] FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE FALSE
> !grepl("K",d$z)
 [1] TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE