How To: Calculate the values of one field to another field of a coverage


After adding a new field to a coverage attribute table, that field can be populated based on values contained in existing fields. Instructions provided describe how to calculate the values of one field to another field of a coverage.

In Workstation ArcInfo, use CALCULATE or MOVEITEM in ArcEdit, ArcPlot, or INFO. In Desktop ArcInfo, use the Field Calculator as shown below.


1. Prepare coverage for editing.

A. Start an ArcMap session.
B. Open the coverage.
C. Click the layer in Table of Contents (TOC).
D. Click Start Editing in the Editor toolbar.

2. Open the Field Calculator on the field to be populated.

A. Right-click the layer in the TOC.
B. For all records, if nothing is selected, click Open Attribute Table.
C. For selected features, click Selection. On the pop-up menu, click 'Open table for selected features'.
D. Find the desired item.
E. Right-click the field name.
F. On the pop-up menu, click Calculate Values to bring up the Field Calculator menu.

3. Define the calculation.

A. On the Field Calculator menu, check a button for the desired calculation to perform (Number, String, Date).

B. Click the source item in the Fields window. The source item name and the target item appear in the Field Calculator.

C. Click OK. All the values of the source item appear in the target item.

[O-Image] [O] ArcMap Field Calculator image

4. Stop Editing and save edits.

Use the Properties of the layer in ArcCatalog to add new items. See Chapter 10 of the "Using ArcMap" tutorial for more information.