# Editing an Ad Hoc Expression Function

You can edit an ad hoc expression function that you have added as either a calculated column or custom expression.

## About this task

You can change an expression function that you added as a calculated column. For information about editing an expression function that you added as a custom expression,

## Before you begin

You have added an ad hoc expression function and run it in your analysis. Spotfire Analyst is open, and the Data panel is displayed.

## Procedure

1. In the Data panel, click the icon to expand the panel.
   The data table view is displayed.
2. From the data column list, select the expression function column name.
   The data panel displays the column view.
3. Click Edit.
   The Edit Calculated Column dialog is displayed.
4. Edit the Expression as required.
   Be sure you specify the correct types, according to the script.
5. Click OK to save and rerun the data function.
   Review the results of the change in any visualization that uses the function.