Using the ArcGIS Spatial Analyst toolbar to reclassify data
Release 9.2 Last modified May 2, 2007

About reclassifying data

By reclassifying, you can modify the values in an input raster and save the changes to a new output raster.
There are many reasons why you may want to do this, including replacing values based on new information, grouping entries, reclassifying values to a common scale (for example, for use in suitability analysis), setting specific values to NoData, or setting NoData cells to a value.
The Load button enables you to load a remap table previously created by clicking the Save button and applying it to the input raster.
The Save button enables you to save a remap table for later use.
Learn more about reclassifying data
Learn about other tools for reclassifying data
Learn about other Spatial Analyst toolbar functions

How to reclassify data

Replacing values based on new information

1. Click the Spatial Analyst dropdown arrow and click Reclassify.
   
2. Click the Input raster dropdown arrow and click the raster with the values you want to change.
   
3. Click the Reclass field dropdown arrow and click the field you want to use.
   
4. Click the New values you want to change and type a new value.
   
5. Click all other New values (use the Shift key) and click Delete Entries.
   
All other values will remain the same in the output raster.

6. Optionally, click Save to save the remap table.
   
7. Specify a name for the output, or leave the default to create a temporary dataset in your working directory.
   
8. Click OK.
   

Tips

NoData values can be turned into numeric values the same way as replacing any value. Click Classify to classify your old values differently. Click Unique to separate classes of old values into unique values.

Grouping entries

1. Click the Spatial Analyst dropdown arrow and click Reclassify.
   
2. Click the Input raster dropdown arrow and click the raster with the values you want to group.
   
3. Click the Reclass field dropdown arrow and click the field you want to use.
   
4. Click the Old values you want to group (click one, hold the Shift key, and click the next one), then right-click and click Group Entries.
   
5. Give the grouped entry and other Old values the New values you want them to have.
   
6. Optionally, click Save to save the remap table.
   
7. Specify a name for the output, or leave the default to create a temporary dataset in your working directory.
   
8. Click OK.
   

Tips

To ungroup entries, right-click the group and click Ungroup Entries. Click Classify to change the classification of your old values. Click Unique to separate classes of old values into unique values.

Reclassifying values of a set of rasters to a common scale

1. Click the Spatial Analyst dropdown arrow and click Reclassify.
   
2. Click the Input raster dropdown arrow and click the raster with the values you want to prioritize.
   
3. Click the Reclass field dropdown arrow and click the field you want to use.
   
4. Click the New values input box for each entry and prioritize the entries.
   
This is subjective according to your spatial problem—for example, preference, cost, or time.

5. Optionally, click Save to save the remap table.
   
6. Specify a name for the output, or leave the default to create a temporary dataset in your working directory.
   
7. Click OK.
   

Tips

Use the Reclassify dialog box to apply a common scale of values to your rasters when doing suitability modeling. This involves reclassifying each raster on the same scale and giving higher new values to the old values that are more important to consider. Click Classify to change the classification of your old values. Click Unique to separate classes of old values into unique values

Changing the classification of input ranges

1. Click the Spatial Analyst dropdown arrow and click Reclassify.
   
2. Click the Input raster dropdown arrow and click the raster with the values you want to reclassify.
   
3. Click the Reclass field dropdown arrow and click the field you want to use.
   
4. Click the Classify button.
   
5. Click the Method dropdown arrow and choose a classification method to reclassify your input data.
   
6. Click the Classes dropdown arrow and choose the number of classes into which your input data will be split.
   
7. Click OK.
   
8. Modify the New values for your output raster if appropriate.
   
9. Specify a name for the output, or leave the default to create a temporary dataset in your working directory.
   
10. Click OK on the Reclassify dialog box.
    

Tips

If your input values are split into ranges and you want them to be unique values, click Unique. Learn more about Standard classification schemes in ArcMap

Setting specific values to NoData

1. Click the Spatial Analyst dropdown arrow and click Reclassify.
   
2. Click the Input raster dropdown arrow and click the raster with the values you want to set to NoData.
   
3. Click the Reclass field dropdown arrow and click the field you want to use.
   
4. Click the input boxes for the New values you want to change to NoData.
   
5. Click Delete Entries.
   
6. Check the Change missing values to NoData check box.
   
7. Optionally, click Save to save the remap table.
   
8. Specify a name for the output, or leave the default to create a temporary dataset in your working directory.
   
9. Click OK.
   
The values you deleted will be changed to NoData in the output raster.

Tip

You can type "nodata" in the input box for a new value to change an input value to NoData.

Please visit the Feedback page to comment or give suggestions on ArcGIS Desktop Help.
Copyright © Environmental Systems Research Institute, Inc.