---
title: Fill columns
description: Fill missing or all values in specific columns using constants or statistical methods.
category: Data Transforms
tags: [imputation, fill, transformation, nulls, preprocessing]
---
# Fill columns
## Description
The **Fill Columns** activity fills missing or empty cells in one or more selected columns using configurable rules or values. It provides two modes:
- **Fill Empty Cells Only** – Fills only `null` or empty cells using statistical or logical methods such as **mean**, **mode**, **median**, **previous**, or **next** value.
- **Fill Entire Column** – Fills **all** cells in a column (including non-empty ones) with a specified constant value.
> **Use case**:
> Useful when preparing datasets for machine learning, reporting, or transformation steps where consistent and complete data is required.
---
## Input
| Type | Description |
| ---- | ---------------------------------------------- |
| Data | Tabular data with missing or incomplete values |
---
## Output
| Type | Description |
| ---------------- | --------------------------------------------- |
| Transformed Data | Data with columns updated based on fill rules |
---
## Configuration Fields
| Field Name | Required | Description |
| -------------------- | -------- | ------------------------------------------------------------------------------------------------------------------------------------------ |
| **Fill empty cells** | No | Enables filling only empty (`null`) values. If disabled, all cells in the specified columns are filled. |
| **Columns Map** | Yes\* | Mapping of column names to fill method (`Mean`, `Mode`, `Median`, `Previous`, `Next`).
_(Visible only if Fill Empty Cells is enabled)_ |
| **Column Map** | Yes\* | Mapping of column names to constant values.
_(Visible only if Fill Empty Cells is disabled)_ |
| **Include original** | No | If enabled, the original columns are preserved and new columns with filled data are added. |
---
## Sample Input
| ID | Age | Salary | Experience |
| --- | --- | ------ | ---------- |
| 1 | 25 | 50000 | 5 years |
| 2 | | 52000 | |
| 3 | 30 | | 7 years |
| 4 | | 55000 | 10 years |
---
## Sample Configuration 1: Fill Empty Cells with Methods
| Field | Value |
| ---------------- | ------------------------------------------------------ |
| Fill empty cells | true |
| Columns Map | Age → `Mean`, Salary → `Mean`, Experience → `Previous` |
| Include original | false |
## Sample Output 1
| ID | Age | Salary | Experience |
| --- | --- | ------ | ---------- |
| 1 | 25 | 50000 | 5 years |
| 2 | 28 | 52000 | 5 years |
| 3 | 30 | 52333 | 7 years |
| 4 | 28 | 55000 | 10 years |
---
## Sample Configuration 2: Fill Entire Columns with Constant Values
| Field | Value |
| ---------------- | ---------------------------------- |
| Fill empty cells | false |
| Column Map | Age → `25`, Experience → `5 years` |
| Include original | false |
## Sample Output 2
| ID | Age | Salary | Experience |
| --- | --- | ------ | ---------- |
| 1 | 25 | 50000 | 5 years |
| 2 | 25 | 52000 | 5 years |
| 3 | 25 | | 5 years |
| 4 | 25 | 55000 | 5 years |
---
> Use **Include Original** when you want to compare filled vs original data side-by-side without overwriting the input columns.