如何编写带4个参数的R语言ans函数？请求技术指导

Hey there! Let's get your function working correctly—you're close, just a couple of syntax issues to sort out.

The Problems in Your Current Code #

• You used = for equality checks, but in R, we need == to test if two values are equal. = is for assigning values, which is why your code was throwing errors.
• The ifelse() function in R follows the structure ifelse(condition, value_if_true, value_if_false)—you tried passing multiple conditions directly, which doesn't work. We need to nest a second ifelse() to handle the second condition.

Correct Versions of the Function #

Option 1: Using Nested ifelse()

This works great if you need the function to handle vector inputs too:

ans <- function(a, b, x, y) {
  ifelse(a == 1 & b == 1, x, 
         ifelse(a == 1 & b == 0, y, 0))
}

Option 2: Using Standard if-else Statements

If you're only working with single scalar values (not vectors), this version is more readable:

ans <- function(a, b, x, y) {
  if (a == 1 && b == 1) {
    return(x)
  } else if (a == 1 && b == 0) {
    return(y)
  } else {
    return(0)
  }
}

Test It Out! #

Let's verify the function behaves as expected:

ans(1, 1, "Hello", "World")  # Returns "Hello"
ans(1, 0, "Hello", "World")  # Returns "World"
ans(0, 1, "Hello", "World")  # Returns 0
ans(2, 5, "Hello", "World")  # Returns 0

内容的提问来源于stack exchange，提问作者hasan sohail