Restarting a COUNTIF function depending on multiple criteria - google-apps-script

Question

I have a sheet with 4 columns, as shown below:
1
Date
Item Name
Counter
Flag
3
Date 1
Item A
1
4
Date 1
Item B
1
5
Date 2
Item B
2
6
Date 3
Item A
2
1
7
Date 3
Item B
3
8
Date 4
Item A
1
9
Date 5
Item A
2
Currently, I'm using a countif function [=countif(B$2:B2,B2)] to count the number of times a specific item appears in the spreadsheet. However, I need to find a way to restart the counter if there is a 1 in column D. In this case, this would mean that the formula in row 8 column C would be [=COUNTIF(B$8:B8,B8)] and would continue counting until it finds another row with a 1 in column D (e.g., formula in column C row 9 would be =COUNTIF(B$8:B9,B9). It would also ideally check whether there is a prior row with a 1 in column D, not through the order of the sheet, but by checking that it's date is smaller (and yet the closest date with a 1 in column D).
I've written the following script, which sets the row with a 1 in column D to 0 and sets the countif for the starting rows correctly to [=countif(B$2:B2,B2)], but it sets any row after there is a row with a 1 in column D as the same formula, with the starting range at B$2.
function setCountifFormula() {
var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Test");
var data = sheet.getDataRange().getValues();
for (var i = 1; i < data.length; i++) { //iterate through each row
var colBValue = data[i][1]; //get columnB in i
var colAValue = data[i][0]; // get date in i
var colDValue = data[i][3]; // get flag in i
var closestRow = 1; // empty variable
if( colDValue == "1") { //if columnD = 1
sheet.getRange(i+1,3).setValue(0); // set columnC = 0
} else {
for (var j = 1; j < data.length; j++) { //iterate through other rows
if (data[j][1] === colBValue && data[j][3] === "1") { // if columnB in j = ColumnB in i, and flag in row j = 1
var dateToCompare = data[j][0]; //set datetoCompare = date in row j
closestRow = j;
if (dateToCompare < colAValue) {
var range = "B$" + (closestRow + 1) + ":B" + (i + 1);
var formula = "=COUNTIF(" + range + ",B" + (i + 1) + ")";
sheet.getRange(i + 1, 3).setFormula(formula);
} else {
var range = "B$2:B" + (i+1);
var formula = "=COUNTIF(" + range + ",B" + (i+1) + ")";
sheet.getRange(i+1, 3).setFormula(formula);
}
}
}
if (closestRow === 1) {
var range = "B$2:B" +(i+1);
var formula = "=COUNTIF("+range +",B"+(i+1)+")";
sheet.getRange(i+1,3).setFormula(formula);
}
}
}
}
I can post the spreadsheet if needs be. If there is a different way without using scripts or COUNTIF, it'd be appreciated. Thanks!

Answer 1

I'm much better at scripting than complex formulas so here is an example of how I would do it.
function myCountif() {
try {
let values = SpreadsheetApp.getActiveSheet().getDataRange().getValues();
values.shift(); // remove headers
let unique = values.map( row => row[1] );
unique = [...new Set(unique)];
let count = unique.map( row => 0 );
let counts = values.map( row => 0 );
values.forEach( (row,rIndex) => {
let cIndex = unique.findIndex( item => item === row[1] );
count[cIndex] = count[cIndex]+1;
counts[rIndex] = count[cIndex];
if( row[3] === 1 ) count[cIndex] = 0;
}
)
return counts;
}
catch(err) {
console.log(err);
}
}
Reference
Array.shift()
Array.map()
Set Object
Array.forEach()
Array.findIndex()
Arrow function =>