Intro to GIS Exercise #5 – Symbology and Map Layout / Design IUP ...

Why set class ranges manually?
There may already be certain standards or guidelines for mapping your data. For example, temperature
maps are often displayed with 10‐degree temperature bands, or you might want to emphasize features
with particular values, for example, those above or below a threshold value. Whatever your reason, make
sure you clearly specify what the classes mean on the map.
How to set a classification
Setting a standard classification method
1. Right‐click the layer that shows a quantitative value for which you want to change the classification
in the table of contents and click Properties.
2. Click the Symbology tab and click Quantities.
3. Click the Value drop‐down arrow and click the field that contains the quantitative value you want
to map.
4. Click the Normalization drop‐down arrow and click a field to normalize the data.
ArcMap divides this field into the Value to create a ratio.
5. Click Classify.
6. Click the Method drop‐down arrow and click the classification method you want to use.
7. Click the Classes drop‐down arrow and click the number of classes you want to display.
8. Click OK on the Classification dialog box.
9. Click OK on the Layer Properties dialog box.
Tip
� Increase the number of columns shown to see more data values in the histogram.
Editing a class range
1. Right‐click the layer for which you want to set class breaks in the table of contents and click Properties.
2. Click the Symbology tab.
3. If you have not already set a classification method, follow the steps in "Setting a standard classification
method".
4. Click the Range you want to edit.
5. Make sure to click the Range, not the Label.
6. Type a new value.
7. This sets the upper value of the range.
8. Click OK.