[R] NA-values and logical operation

[Patrick Hausmann]

Dear list,

as a result of a logical operation I want to assign
a new variable to a DF with NA-values.

z <- data.frame( x = c(5,6,5,NA,7,5,4,NA),
                  y = c(1,2,2,2,2,2,2,2) )

p <- (z$x <= 5) & (z$y == 1)
p
z[p, "p1"] <-5
z
# ok, this works fine

z <- z[,-3]

p <- (z$x <= 5) & (z$y == 2)
p
z[p, "p2"] <-5
z
# this failed... - how can I assign the value '5' to the new
# var "p2"

Thanks for any help!!
Patrick