Categorical symbology

Render each feature differently based on the value of one field. Status colors, asset types, land use classes.

basic

Categorical symbology picks a fill / stroke / icon per feature based on the value of one field. Use for status colors, inspection results, asset type, land-use codes, anything where the field has a small set of discrete values that each deserve a distinct look.

Inputs

  • A layer on the map.
  • A field that drives the symbology. Most useful when the field's values are bounded (an enum, a pick list, a status code).
  • A class per value: each known value gets its own fill / stroke / icon / size.
  • A fallback class for values not in the list (or NULL).

How to set it

  1. In the map builder's layer style panel, pick Categorical.
  2. Pick the field.
  3. Click Auto-fill from values to populate one class per distinct value in the layer. The portal samples the layer and adds an entry per value.
  4. Adjust each class's symbol (fill, stroke, icon, size).
  5. Either accept the fallback class or set "no value" features to invisible.
  6. Save the map.

If the field is bound to a pick list item, the importer pre-fills class names from the pick list labels and color from the pick list color (when set). Adding a new pick list entry later doesn't auto-create a class on this layer; you re-open the style panel and pick the new value.

Examples

  • Inspection status: passed → green, needs-repair → amber, failed → red, anything else → gray.
  • Hydrant type: dry → blue, wet → cyan, private → yellow.
  • Land use: 12 codes from the local zoning ordinance, each with its own fill color matching the printed map legend.

Notes

  • NULL is a value too. If you don't add a class for NULL, the fallback handles it. Common pattern: NULL features become a light-gray outline so they're visible but obviously incomplete.
  • Don't categorize on a high-cardinality field. Don't pick categorical on a field with hundreds of distinct values; the legend becomes unreadable and the render slows. Use Graduated (for numeric) or filter to a subset.
  • Order of classes matters when values overlap visually (large polygons cover smaller ones). The order in the style panel is the draw order; drag to reorder.