Fiddler is a way to handle spreadsheet data in a functional way, as described in A functional approach to fiddling with sheet data
This class – Fiddler can be found in my cUseful library.
Here’s the key, and it’s also on github
Mcbr-v4SsYKJP7JMohttAZyz3TLx7pV4j
There’s a video of how to use it below
Manipulating unique values.
One common operation on spreadsheet data is to deal with unique values. Fiddler has a couple of new methods to reduce spreadsheet data to unique values. For a full description of the many things that Fiddler can do, see A functional approach to fiddling with sheet data
method | arguments | returns | purpose |
.filterUnique | columnNames – an single or array of column names. If missing all columns are used for filtering. keepLast – whether to use the first or last occurrence of a row when duplicate is found compareFunction – an optional function to compare values. should return a boolean – true if values are equal | fiddler for chaining | Reduces the data held in the fiddler to get rid of duplicate rows. A duplicate row is where the values in all the columns mentioned in the columnNames argument are exactly the same for a given row. If columnNames is blank, then the entire row needs to be identical for there to be a duplicate default is function (a,b) { return a===b ; } |
.getUniqueValues | columnName – the columnName to return the values of compareFunction – an optional function to compare values. should return a boolean – true if values are equal | An array of values | Returns the unique values in the column specified. default is function (a,b) { return a===b ; } |
Example with custom compare functions. These are sheets focused, but fiddler can be used with any data arrays. The input data is

function removeDuplicates() { var ss = SpreadsheetApp.openById('1181bwZspoKoP98o4KuzO0S11IsvE59qCwiw4la9kL4o'); var sheet = ss.getSheetByName("remove-duplicates"); // this one will remove duplicates rows using a fiddler // https://ramblings.mcpher.com/google-apps-scripts-snippets-2/unique-values-with-data-fiddler?preview_id=5996&preview_nonce=32bc8981f9&preview=true // get the values, remove duplicate rows - a duplicate defined as same first/last name var fiddler = new cUseful.Fiddler(sheet); // A. get all the unique values in a given column Logger.log (fiddler.getUniqueValues("first name")); // B. get all the unique values in a given column, with a custom compare function Logger.log (fiddler.getUniqueValues("first name", function (a,b) { return a.toLowerCase() === b.toLowerCase(); })); // C. remove duplicates using multiple columns // and write back to a different sheet (creating it if necessary) fiddler.filterUnique (["first name","last name"]) .dumpValues (ss.getSheetByName ("dupremove") || ss.insertSheet ("dupremove")); // D.remove duplicates, with a custom compare function // and write back to a different sheet (creating it if necessary) var fiddler = new cUseful.Fiddler(sheet) .filterUnique (["first name","last name"] ,false , function (a,b) { return a.toLowerCase() === b.toLowerCase(); }).dumpValues (ss.getSheetByName ("customdupremove") || ss.insertSheet ("customdupremove")); // E. remove duplicates, with a custom compare function , and keep the last occurrence // and write back to a different sheet (creating it if necessary) var fiddler = new cUseful.Fiddler(sheet) .filterUnique (["first name","last name"] ,true , function (a,b) { return a.toLowerCase() === b.toLowerCase(); }).dumpValues (ss.getSheetByName ("customdupremovelast") || ss.insertSheet ("customdupremovelast")); }
Results
D. create a new sheet with with duplicate first/last name combinations removed, and a custom function to ignore case
E. create a new sheet with with duplicate first/last name combinations removed, and a custom function to ignore case, keeping the last occurrence (instead of the first)

The code
Mcbr-v4SsYKJP7JMohttAZyz3TLx7pV4j
More on this topic available here
- A functional approach to fiddling with sheet data
- Unique values with data fiddler
- More sheet data fiddling
- Fiddling with text fields that look like dates
- A functional approach to updating master sheet
- Populating sheets with API data using a Fiddler
- Header formatting with fiddler
- Formatting sheet column data with fiddler
- Styling Gmail html tables
- Sorting Google Sheet DisplayValues
- A functional approach to fiddling with sheet data
- A functional approach to updating master sheet
- A recursive extend function for Apps Script
- A webapp to share copies of the contents of folders
- Abstracting services with closures
- Add-on spinner
- Addressing namespace and library methods from google.script.run
- Anonymous user registration with the Apps Script PropertiesService
- Apps for Office – binding example comparison
- Apps Script as a proxy
- Apps Script const scoping problems
- Calculating image dimensions in server side apps script
- Calculating the last day of a given weekday in the month
- Canvasser
- Chaining JavaScript
- Changing class properties dynamically
- Checking the argument types in Apps Script
- Cleaning up a document format
- Cleaning up heading levels
- Column numbers to characters
- Composing functions and functional programming
- Configurable canvas meter
- Convert JSON to XML
- Converting SVG to PNG with JavaScript
- Converting timestamps to dates formula
- Copying canvas and svg images from your Add-on
- Copying to new host location
- Copying to new host location
- Counting script and library usage
- Create sha1 signatures with apps script
- Creating a key digest to use for a cache key or to compare content
- Creating a pile of files list from Google Drive
- Creating and working with transposed sheet data arrays
- Cross Origin Resource sharing (CORS)
- CryptoJS libraries for Google Apps Script
- Custom checking for exponential backoff
- Data wrangling with named columns in Google Spreadsheet
- Dealing with objects that are too large for the property or cache store
- Detecting Spreadsheet tables automatically with Google Apps Script
- Direction minimizer – other usages
- Do something useful with GAS in 5 minutes
- Dynamically creating tables with clusterize.js
- EasyCron Library
- ES6 JavaScript features
- Exponential backoff
- Exponential backoff for promises
- Fiddler and rangeLists
- Fiddling with text fields that look like dates
- Filling ranges in Google Sheets
- Finding a Drive App folder by path
- Finding where Drive hosting is being used in Sites
- Flattening an object with dot syntax
- Flattening and unflattening objects to spreadsheets
- Formatting GraphQL queries
- Formatting sheet column data with fiddler
- From notes to frequencies and back again
- From Xml to JSON
- Generating and managing random lists with JavaScript and Apps Script
- Generating coupon codes with expiry dates
- Generating test data for sheets and tables
- Get GAS library info
- Getting an htmlservice template from a library
- Getting insights into Sheets performance
- Google Drive as cache
- Header formatting with fiddler
- Highlight duplicate rows in a sheet – map and reduce
- Highlight duplicate rows in a sheet – map, filter and every
- How to determine what kind of object something is in Apps Script
- How to get stats about youtube videos in your channel with apps script
- How to pass non stringifyable objects to html service
- How to transpose spreadsheet data with apps script
- Identify duplicates on Drive
- Identifying hosted files
- Implementing a client side progress bar reporting on server side work for htmlService
- Importing Predictwise data
- Improved namespace pattern for Apps Script
- Including the stack in custom errors
- JavaScript closures – how, where and why
- JavaScript currying and functional programming
- JavaScript currying and functional programming – even more
- JavaScript recursion primer
- JSONP and JSON and Google Apps Script webapps
- Loading large JSON datasets into BigQuery with Apps Script
- Logging differences in strings in Apps Script
- Measuring library load speed
- Migrating user and script properties
- Minimizing maps directionfinder api calls
- More client server code sharing
- More recursion – parents and children
- More sheet data fiddling
- Multiple inserts in Fusion Tables
- Namespaces in libraries and scripts
- Normalizing the header level of blank paragraphs
- Optimizing sheet formatting with Apps Script
- Optimizing showing and hiding rows and columns
- Organizing asynchronous calls to google.script.run
- Organizing parallel streams of server calls with google.script.run promises
- Parallel process orchestration with HtmlService
- Passing data to html service
- Patching site html
- Populating sheets with API data using a Fiddler
- Proxy jsonp
- Pseudo binding in HTML service
- Queuing asynchronous tasks with rate limit and concurrency constraints
- Recursive async functions
- Removing duplicate paragraphs
- Reporting file, function and line number in Apps Script
- Resumable uploads – writing large files to Drive with Apps Script
- Reusing html stuff between Apps Script projects
- Roughly matching text
- Serving apps script to JavaScript app
- Sharing code between client and server
- Shortcut for adding nested properties to a JavaScript object
- Simple server side polling
- Sorting Google Sheet DisplayValues
- Squeezing more into (and getting more out of) Cache services
- Styling Gmail html tables
- Summarizing emails to a sheet
- SunCalc
- TimeSimmer : An adjustable timer for apps that need to speed up or slow down time
- Transform dates for add-on transfer
- Transposing sheet data
- Traversing a tree
- Unnesting data to sheet values
- Untangling with promises
- Use Drive properties to find app files
- Use promise instead of callback for settimeout
- Using Advanced Drive service to convert files
- Using Apps Script for xml json conversion
- Using array formulas to improve performance
- Using crossfilter with Google Apps Script
- Using D3 in server side Gas
- Using es6 promises server side in Apps Script
- Using Es6 with Apps Script
- Using exponential backoff with github api – dealing with data “in preparation”
- Using Google sheets via Bigquery from Apps Script
- Using named locks with Google Apps Scripts
- Using promises to orchestrate Html service polling
- Using promises with apps script
- Using the Itunes API with Apps Script
- Using the slideshare API from Apps Script
- Using timing functions to get insight into Sheets
- Watching docs for changes
- Watching for server side changes from the client html service
- What JavaScript engine is Apps Script running on?
- Why Base64
- Zipping to make stuff fit in cache or properties service.
Why not join our forum, follow the blog or follow me on Twitter to ensure you get updates when they are available.