How To: Symbolize polygons according to what percentage of total area they represent
Instructions provided describe how to symbolize polygons according to what percentage of total area they represent.
Calculate the area of each feature to one field and the total area of all features to a second field. Divide the first field by the second field and place the resulting values into a third field, which is used as the 'Value' field for the layer symbology.
- Generate area values for all polygon features and store them in Field A.
- Right-click Field A, select 'Statistics', and note the 'Sum' value.
If interested in doing this on subsets of the data, perform a series of 'Select by Attributes' operations. For example, "Land Use = Federal". Do this for each selection set, taking note of the sum for each subset.
- Create Field B and use the Field Calculator to attribute the entire field to populate the records with the appropriate sum value.
For selected subsets, calculate the field values only for the selected records.
- Create Field C and using the Field Calculator calculate Field C equal to Field A divided by Field B.
- Symbolize the data based on Field C.