Create serial count in column if adjacent cell is blank (Google Sheets)

Question

I'm trying to create a simple counting ArrayFormula that iterates by one, if adjacent cell is empty (doesn't contain "IGNORE"). E.g. COUNT column here should only count when STATUS <> IGNORE:

ROW   STATUS    COUNT
______________________
1     IGNORE    
2     IGNORE
3                 1
4                 2
5                 3
6     IGNORE
7     IGNORE
8                 4
9                 5

What ArrayFormula can I use here in cell C1 COUNT?

Answer 1

You can create a custom function and integrate it with ARRAYFORMULA.

Example

Code:

function countNonIgnore(values) {
  var tempArr = [];
  var ctr = 1;
  values.forEach(val => {
    if(val[0] == "IGNORE"){
      tempArr.push([""]);
    }else{
      tempArr.push([ctr]);
      ctr++;
    }
  })
  return tempArr;
}

Output:

Reference:

• Custom Functions in Google Sheets