Maps
Dorling cartogram
Replaces regions with value-scaled non-overlapping circles near their geographic positions.
- Map
- Geography
- Magnitude
What it answers
How do regional totals compare as circles?
- Shape
- Geographically arranged circles
- What it shows
- Magnitude and broad geographic grouping.
Example
The question
How do regions compare in revenue, keeping rough positions?
Regions as circles sized by revenue (Dorling cartogram)
Illustrative data. It belongs to no company.
When to use it
Use it when
Showing totals with less irregular-shape influence.
Avoid it when
When exact locations or boundaries matter.
How to read it
Read region labels and circle areas, using approximate geographic positions.
Note
Positions approximate geography.
The data you need
- Layout
- Attribute table plus geographic boundaries
- Fields
- RegionID: text; Value: number; matching polygon geometry or geographic boundary source
- One row is
- One region and its measured value. What is the grain?
- Rules
- Join data to boundaries with stable IDs. Declare geographic level, boundary version and coordinate reference system.
- Optional
- Names alone may be ambiguous. Geometry can be GeoJSON, a spatial file or a tool-supported boundary lookup.
- Preparation
- Convert region values to circle areas and use a Dorling layout that reduces overlap while approximating geography.
- Units
- State the mapped attribute unit, geographic level and boundary/coordinate reference. Rates need an explicit population or area denominator.
Worked example
RegionsA60, B40 become circles with area ratio 3:2. Circle centres may shift to avoid overlap.
| RegionID | Value |
|---|---|
| R1 | 30 |
| R2 | 45 |