r - 解释来自 "condition has length > 1"函数的 `if` 警告

Question

我有一个数组:

a <- c(0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0)

并且想实现以下功能:

w<-function(a){
  if (a>0){
    a/sum(a)
  }
  else 1
}

此函数想要检查 a 中是否有大于 0 的值，如果有，则将每个元素除以总和。

否则它应该只记录 1。

我收到以下警告消息:

 Warning message:
 In if (a > 0) { :
 the condition has length > 1 and only the first element will be used

如何更正该功能？

Answer 1

也许你想要ifelse:

a <- c(1,1,1,1,0,0,0,0,2,2)
ifelse(a>0,a/sum(a),1)

 [1] 0.125 0.125 0.125 0.125 1.000 1.000 1.000 1.000
 [9] 0.250 0.250