Google Apps 脚本：为什么这种排序不起作用？

Question

new to google apps script and trying to find the second highest value in a range. When I input a range like [45, 101, 100, 40] the value returned is 101 . Clearly the sort() isn't working as it is just returning the second value in the range. What am I missing?

function second_max(range) {
  if (range) {
    var arr = [];
    for (var i = 0; i < range.length; i++) {
      arr.push(range[i]);
    }
    arr.sort();
    Logger.log(arr);
    return arr[1];
  }

}

Answer 1

change arr.sort() to arr.sort(function(a, b){return ab}) .

It doesn't sort because it thinks it's a string. For example, [1, 5, 2, 100, 500, 250, 60, 55, 100000] will be sorted to [1, 100, 100000, 2, 250, 5, 500, 55, 60].

So, you'd better to implement subtraction callback function inside of sort() so that you can get the right result.

check this out: https://www.w3schools.com/jsref/jsref_sort.asp

Answer 2

Issue:

• range is a two dimensional array - array of arrays(eg: [[45], [101], [100], [40]] ). arr.sort can sort only numbers.

Solution(s):

You can try any of the following:

• You can easily use inbuilt formulas like SORTN to do the same:

   =INDEX(SORTN(A1:A20,2),2)

• Pass a compareFunction to parse the array and sort.

• Flat ten the array and use Math.max

Snippet:

// Will only work for vertical rows as horizontal ranges like A1:C1 looks like [[1,2,3]]; Modify it accordingly.
function second_max(arr) {
  return arr.sort(([a],[b])=>b-a)[1][0];
}

/* Works with any 2D array*/
function second_max2(arr) {
  let flatArr = arr.flat();
  let max1 = Math.max(...flatArr);
  return Math.max(...flatArr.filter(num=>num !== max1))
}