Question

我有一个名为A的矩阵，我想在给定坐标的情况下检索它的元素。我做了坐标转换。这是我执行此任务的代码，但我不知道，为什么我会收到错误。有人能帮助我吗？它从用户获取坐标（i，j）并在坐标处检索矩阵元素。错误是：

意外的输入结束

    p<- as.numeric(readline(prompt="Pleae enter 1 to get coordinate of number,and 2 to get the number > "));

    if(p==1){
    # get the number, given coordniate 
     i<- as.numeric(readline(prompt="Pleae enter i cordinate > "));
     j<- as.numeric(readline(prompt="Pleae enter j cordinate > "));
    Getvalue<- function(i,j){
        if (i>=0) A[2+i,2+j]
        else      A[2+i,2-j]

        Getvalue
    }else if (p==2){
   # do this 
}

Answer 1

这适合我。

foo <- function(){
p<- as.numeric(readline(prompt="Please enter 1 to get coordinate of number, and 2 to get the number > "))

if(p==1){
  # get the number, given coordniate 
  i<- as.numeric(readline(prompt="Please enter i cordinate > "))
  j<- as.numeric(readline(prompt="Please enter j cordinate > "))
  Getvalue <- function(i,j){
    if (i>=0) {
      return(A[2+i,2+j])
    } else{
      return(A[2+i,2-j])
    }      
  }
  Getvalue(i, j)
} else  if (p==2){
  print("Do this")
  }

}

###Example:
> # a dummy matrix 
> set.seed(1)
> A <- matrix(sample(100, 100, TRUE), 10)
> # If p=1, i=2, j=2, then 19 should be returned.

> foo() # executing `foo()` to values from the terminal 
Please enter 1 to get coordinate of number, and 2 to get the number > 1
Please enter i cordinate > 2
Please enter j cordinate > 2
[1] 19
> foo()
Please enter 1 to get coordinate of number, and 2 to get the number > 2
[1] "Do this"

阅读readline的文档，并尝试理解其中显示的示例。

多个if，else语句和获取错误。

1 个答案: