R: Usage of NULL

Peter Lin

2018/4/4

The first method:

min=function(x){
  s=NULL
  for (i in x){
    if (is.null(s))  s=i  else if (i<s) s=i
  }
  return (s)
}


min(c(3,6,3,2))

## [1] 2

The second method:

Be careful about or logical, using ‘||’ not ‘|’

min2=function(x){
  s=NULL
  for (i in x){
    if (is.null(s) || i<s) {s=i}
  }
    return (s)}


min2(c(13,6,5,21))

## [1] 5