解释“条件的长度为> 1"来自if函数的警告

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)

，并希望实现以下功能:

and would like to implement the following function:

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

此功能想检查a中是否有大于0的值，如果是，则将每个元素除以总和.

This function would like to check whether there is any value in a larger than 0 and if yes then divide each element by the sum of the total.

否则，它应该只记录1.

Otherwise it should just record 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

如何纠正该功能?