if expression or
an
if-
else expression is possible.
if(test) true.expr if(test) true.expr else false.expr e1 || e2 e1 && e2
if construct in the language evaluates
test.
If it is
TRUE (i.e., if the first element of the result coerced to
mode
logical is
TRUE), then
true.expr
is evaluated and returned as the value of the whole expression.
Otherwise, the value of the expression is
false.expr if present, or an
empty value otherwise.
TRUE if both of its operands are
TRUE (in the same sense
as
test above). If the left operand is not
TRUE, the right operand
is not evaluated.
TRUE if one of its operands is
TRUE (in the same sense
as
test above). If the left operand is
TRUE, the right operand
is not evaluated.
An
NA value for the test causes an error.
A zero length logical vector causes an error if passed as the left operand for
||
or passed as either operand for
&&.
The && and || operators are members of the
Ops group of generic
functions.
if(mode(x)!="character" && min(x)>0) log(x)
# log(x) is an error if mode(x) is "character"
if(is.na(okay)) z <- z+1 else if(okay) {y <- rnorm(1); x <- runif(1)}