The difference between & and && in R

Question

I have read

http://stat.ethz.ch/R-manual/R-devel/library/base/html/Logic.html

and the difference between & and && doesn\'t make sense. For examp

Answer 1

Consider this, then it should be clear:

as.logical(c(0,1,2,3,4))
#[1] FALSE  TRUE  TRUE  TRUE  TRUE

So...

c(1,2,3) & c(1,3,3)
#[1] TRUE TRUE TRUE

is equivalent to:

c(TRUE,TRUE,TRUE) & c(TRUE,TRUE,TRUE)

...which compares by element using & and returns c(TRUE,TRUE,TRUE)

For reference:

test <- c(NA,NaN,-Inf,-1,-0.5,0,0.5,1,2,Inf)
data.frame(test,as.logical(test))

#   test as.logical.test.
#1    NA               NA
#2   NaN               NA
#3  -Inf             TRUE
#4  -1.0             TRUE
#5  -0.5             TRUE
#6   0.0            FALSE
#7   0.5             TRUE
#8   1.0             TRUE
#9   2.0             TRUE
#10  Inf             TRUE