LAMBDA: the day Excel let you write your own functions
Copy-pasting the same formula across a workbook used to be the only way to reuse logic - until LAMBDA let you name it and call it like any other Excel function.
LAMBDA
// 16 postsTutorials, tips, and deep dives on LAMBDA — every post from bianca.codes tagged LAMBDA.
LAMBDA posts
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Your nested IF statements are technical debt
A formula with six nested IFs works fine, right up until the rule changes and you're reverse-engineering a 300-character one-liner you wrote six months ago.
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REDUCE: How to Build Running Calculations Across Any Dimension in Excel
REDUCE is the most powerful of the functional array functions and the most overlooked. The lambda which means you can accumulate strings, and replace calculations that used to need VBA.
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3-Minute Win: Use REDUCE to Concatenate a Column of Values Into One Cell
Joining a column of names or tags into one comma-separated string used to need TEXTJOIN or a helper column. REDUCE does it in one formula, and lets you transform each item before it gets concatenated.
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Excel Is Quietly Becoming a Programming Language and Most Users Haven't Noticed
LAMBDA, MAP, REDUCE, SCAN, BYROW. These are functional programming primitives. Excel is shipping them one by one, and most users are still writing nested IFs. The spreadsheet you learned in 2015 has been quietly replaced by something much more powerful.
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Build a Dynamic Summary Table Using BYROW and LAMBDA — No Pivot Table Required
You'll build a summary that calculates a custom metric for every row in your dataset without a pivot table, without helper columns, and without copying formulas down. BYROW plus a LAMBDA gives you …
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BYROW and BYCOL: Apply Any Formula to Every Row or Column, Automatically
BYROW hands your function an entire row at a time. BYCOL does the same by column. Together they replace an entire category of 'drag this formula down and keep it updated' work — and when you combin…
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The Excel Functions Your Spreadsheet Has Been Missing for Ten Years
XLOOKUP, LET, LAMBDA, BYROW, SCAN, MAP — Microsoft shipped more genuinely useful functions in the last three years than in the previous decade. If you learned Excel before 2022 and haven't revisite…
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3-Minute Win: Use BYROW to Apply a Formula to Every Row Without Dragging It Down
BYROW hands your function an entire row at a time — which means 'apply this logic to every row in this range' is one formula in one cell. No dragging, no CTRL+SHIFT+ENTER, no missing the last row w…
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Stop Using Helper Columns for Running Totals — There's a Better Way
Helper columns aren't wrong. But when a running total requires three of them and breaks every time someone inserts a row, you've created fragility in exchange for familiarity. The Excel array funct…
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Build a Rolling 12-Month Balance Tracker That Updates Without Touching a Formula
You'll build a balance tracker using SCAN and a structured table that extends itself as new rows come in. No helper columns, no fragile cell references, no 'just re-paste the formula down.' Add a r…
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SCAN: The Excel Function That Keeps a Running Total of Anything
Running totals used to mean helper columns or array gymnastics. SCAN changes that — it applies a function cumulatively across an array and hands you back every intermediate result. Once you see it …
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Excel Formulas Are Getting Too Complex - And LAMBDA Is Why That's Actually Fine Now
The counter-argument to 'if your formula needs a scrollbar to read, it's wrong.' With LAMBDA, complexity lives in one named place and gets called cleanly everywhere else. The formula in your cell c…
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LAMBDA: How to Write the Excel Functions Microsoft Didn't
Before LAMBDA, every Excel function that existed was one Microsoft decided to write. After LAMBDA, you can write them yourself — naming the logic, hiding the complexity, and calling your custom fun…
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3-Minute Win: Name Your LAMBDA Function and Call It From Any Cell in the Workbook
One function definition in the Name Manager, and every cell in the workbook can call it like a built-in. LAMBDA + named functions means you stop copy-pasting logic and start writing like someone wh…
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Build a Drop-In XLOOKUP Upgrade for Every VLOOKUP in Your Workbook
Stop replacing VLOOKUPs. Your workbook deserves XLOOKUP without touching the formula.