if ( condition ) {
command1
} else {
command2
}
if ( condition ) {
command1
} else if (cond) {
command2
} else if (cond) {
command3
} else command4
if ( x > 100 ) y=1 else y=0
if ( x > 100 ) { y=1 } else { y=0 }
if ( is.character(x) ) 1 else 5
for (i in 1:20) command
for (i in 1:length(x))
for (i in v) {
command1
command2
}