Removing Duplicates in Google Sheets: A Guide for Non-coders

Ugh.., I have so many duplicate rows in my spreadsheet. Well so do many other people. With the script in this article, you can introduce a menu button that lets you delete duplicate rows in your spreadsheet.

This blog is the second part of the blog I published a few days ago: “How to Highlight Duplicate Rows in Google Sheets?”. There I provided a simple script to highlight duplicate rows. This script will extend that script to delete those duplicate rows.

For Non-Coders

If you’re not a coder and don’t wanna be bothered with an explanation then follow this step:

1. Open Script editor. On your spreadsheet click the Extensions tab and then Apps Script as shown in the image above.

2. Remove all the codes in Code.gs. Then copy and paste the code from the Full Code section in this blog.

3. Save and then reload the spreadsheet. Now, reopen the Apps script as instructed in step 1 (Sometimes the script doesn't work without saving and reloading).

If you’re already using the previous script then you can just copy and paste this script over the previous one.

Full Code

Here’s the full script for this blog including the previous blog’s code.

/**
 *The colorDuplicateRows() colors the duplicate rows.
 *Each unique rows and its duplicates are highlighted with different color
 */
function colorDuplicateRows() {
  // get sheet and data
  let sheet = SpreadsheetApp.getActiveSheet();
  let data = sheet.getDataRange().getValues();

  // find lastCol
  let lastCol = Math.max(...data.map((arr) => arr.length));

  // convert nested arrays to string
  data = data.map((arr) => arr.join(""));
  // find unique ones among arrays
  let uniqueRows = [...new Set(data)].filter(String);
  // create unique color for each unique arr
  let uniqueColor = {};
  uniqueRows.forEach((val) => (uniqueColor[val] = getRandomUniqueColor()));

  // console.log(uniqueColor);
  // find duplicate row for each item
  let duplicateRows = data
    .map((x, i) => (isDuplicateRow(x, data) ? i + 1 : ""))
    .filter(String);
  // console.log(duplicateRows);

  // now reset color before highlighting duplicate rows
  colorReset();

  duplicateRows.forEach((rowNum) => {
    for (let i = 0; i < uniqueRows.length; i++) {
      //console.log(range.getValues())
      // compare each item with uniqe items and assing color accordingly
      if (
        sheet.getRange(rowNum, 1, 1, lastCol).getValues().flat().join("") ===
        uniqueRows[i]
      ) {
        sheet
          .getRange(rowNum, 1, 1, lastCol)
          .setBackground(uniqueColor[uniqueRows[i]]);
      }
    }
  });
}

/**
 * Function takes two items: row and arr.
 * The parameter "row" is a string to be compared to items in array "arr".
 * Inspired from https://stackoverflow.com/a/68424642/6163929
 * @param {String} row
 * @param {Array<String>} arr
 * @returns {Boolean}
 */
function isDuplicateRow(row, arr) {
  return row === "" ? false : arr.indexOf(row) != arr.lastIndexOf(row);
}

/**
 * Menu creates menu UI in spreadsheet.
 */
function createCustomMenu() {
  let menu = SpreadsheetApp.getUi().createMenu("Highlight Duplicate Rows"); // Or DocumentApp or SlidesApp or FormApp.

  menu.addItem("Highlight Duplicate Row", "colorDuplicateRows");
  menu.addItem("Delete Duplicate Row", "deleteDuplicateRows");
  menu.addItem("Reset Colors", "colorReset");
  menu.addToUi();
}

/**
 * OnOpen trigger that creates menu
 * @param {Dictionary} e
 */
function onOpen(e) {
  createCustomMenu();
}

/**
 * ColorReset is used to reset bg color of spreadsheet to its original color.
 */
function colorReset() {
  let sheet = SpreadsheetApp.getActiveSheet();
  sheet.getDataRange().setBackground("");
}

/**
 * Function creates a unique random color as hashcode.
 * @returns {String}
 */
function getRandomUniqueColor() {
  // thanks to function https://dev.to/rajnishkatharotiya/generate-unique-color-code-in-javascript-3h06
  let n = (Math.random() * 0xfffff * 1000000).toString(16);
  return "#" + n.slice(0, 6);
}


/**
 *The deleteDuplicateRows() funciton deleted the duplicate 
 *rows in current active spreadsheet.
 */
function deleteDuplicateRows() {
  // get sheet and data
  let sheet = SpreadsheetApp.getActiveSheet();
  let data = sheet.getDataRange().getValues();



  // convert nested arrays to string
  data = data.map((arr) => arr.join(";"));
  // find unique ones among arrays
  let uniqueRows = [...new Set(data)].filter(String);
  // convert the values from string to qrray again
  let newData = uniqueRows.map(itemStr => itemStr.split(";"));

  // find last row and col for new range.
  let newLastRow = newData.length;
  let newLastCol = Math.max(...newData.map((arr) => arr.length));

  // reset previous colors if the highlight function is used
  colorReset();


  // clear previous contents to save only unique values
  sheet.clearContents();
  // set new values
  sheet.getRange(1, 1, newLastRow, newLastCol).setValues(newData);

}


/**
 * Code By Nibesh Khadka.
 * I am freelance and Google Workspace Automation Expert.
 * You can find me in:
 * https://linkedin.com/in/nibesh-khadka
 * https://nibeshkhadka.com
 * me@nibeshkhadka.com
 */

deleteDuplicateRows() is the new function added to the script of the previous blog. Also, the menu item is extended to add the function.

Similar to the previous blog, you can now just:

1. Save the code.

2. Reload the spreadsheet.

3. And execute the function.

You’ll able to see the menu with the title “Highlight Duplicate Rows“.

Now, you can check duplicate rows in your spreadsheet and delete them if you want with ease.

Thank You for Your Time

I make Google Add-Ons and can also write Google Apps Scripts for you. If you need my services let me know.

Don’t forget to like and share this blog.