Check if value is in data frame

Question

I'm trying to check if a specific value is anywhere in a data frame.

I know the %in% operator should allow me to do this, but it doesn't seem to work the way I would expect when applying to a whole data frame:

A = data.frame(B=c(1,2,3,4), C=c(5,6,7,8))
1 %in% A

[1] FALSE

But if I apply this to the specific column the value is in it works the way I expect:

1 %in% A$C

[1] TRUE

What is the proper way of checking if a value is anywhere in a data frame?

Answer 1

You could do:

any(A==1)
#[1] TRUE

OR with Reduce:

Reduce("|", A==1)

OR

length(which(A==1))>0

OR

is.element(1,unlist(A))