[R] ?Bug: '&&' and '&' give different results?

[andreas at jostel.com]

"&&" seems to behave strangely and gives different results from "&" e.g. in a data frame selection (regardless whether terms are bracketed)?

===========Script=======================

test=data.frame(gender=c("F","M","M","F","F"),side=c("R","L","R","L","R"))
test
test[test$gender=="F" & test$side=="R",]
test[test$gender=="F" && test$side=="R",]

=============Output:=====================
> test=data.frame(gender=c("F","M","M","F","F"),side=c("R","L","R","L","R"))
> test
  gender side
1      F    R
2      M    L
3      M    R
4      F    L
5      F    R
> test[test$gender=="F" & test$side=="R",]
  gender side
1      F    R
5      F    R
> test[test$gender=="F" && test$side=="R",]
  gender side
1      F    R
2      M    L
3      M    R
4      F    L
5      F    R