A GAS to Removes Duplicates based on a column value

[Hussein Osseily]

Good day Everyone,

I have this script that it should remove duplicates (deleting the whole row) based on the value in Column C
If column has the value "Red" 4 for example it should delete 3 rows and keep the unique one (1 time)I tested it with an example, lets say column C has "Red" 10 times the script is deleting 3 rows, then am having to run it again to delete another 4 Rows and then run it again to delete the rest and keep 1 Unique Row.

Appreciate any help here, thanks in advance.

The Script: 

function removeDuplicates() {

  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Sheet1");

  var data = sheet.getDataRange().getValues();

  var unique = {};

  

  // Loop through the data array and remove all but the first occurrence of each unique value in column C

  for (var i = 0; i < data.length; i++) {

    var value = String(data[i][2]).trim().toLowerCase(); // clean up the value before checking

    if (unique[value]) {

      sheet.deleteRow(i+1);

    } else {

      unique[value] = true;

    }

  }

  

  // Loop through the unique object and remove any duplicates after the first occurrence

  for (var value in unique) {

    var count = 0;

    for (var i = 0; i < data.length; i++) {

      if (String(data[i][2]).trim().toLowerCase() === value) { // clean up the value before checking

        count++;

        if (count > 1) {

          sheet.deleteRow(i+1);

        }

      }

    }

  }

}

[Tanaike]

In your situation, how about using a method of "removeDuplicates" of Class Range? When this method is used, a sample script is as follows.

function removeDuplicates() {
  var sheet = SpreadsheetApp.getActiveSpreadsheet().getSheetByName("Sheet1");

  sheet.getDataRange().removeDuplicates([3]);
}

By this modification, when this script is run the duplicated rows are deleted with the column "C". If I misunderstood your expected result, I apologize.