Filling or splitting polygons proportionally based on variables using QGIS?

Question

I want to divide each country into three separately coloured areas, like this:

The proportions of the three coloured areas must based on three columns of attribute data in the country shapefile's attribute table (representing percentages of a country's total energy production).

The two ways I can think of doing this are:

1. Using a fill method to colour each country with three different solid colours proportionally based on the attribute data, or
2. To split each country's polygon into three polygons proportional to the attribute data (and then they can easily be given separate colours).

For the first method, the only solution I have found is Ed Rollason's technique using gradients, but I want to achieve the same thing using solid colours, not gradients.

For the second method, there is the Split Polygon plugin but that doesn't allow one to use attribute variables.

Does anyone know a method to achieve this?

Answer 1

How to fill a polygon with stripes where the width of each stripe is proportional to an attribute

Build a multi-layered symbol from the bottom up, with layers as follows.

• Final layer - outline

  Symbol Layer Type: Outline: Simple Line

• Fourth layer and higher - follow the pattern set by the second and third layers below

• Third layer - attribute3

  Symbol Layer Type: Geometry Generator

  • Geometry type: Polygon/Multipolygon
  • Expression: intersection($geometry, translate(bounds($geometry), ("attribute2"/100)*bounds_width($geometry), 0))

• Second layer - attribute2

  Symbol Layer Type: Geometry Generator

  • Geometry type: Polygon/Multipolygon
  • Expression: intersection($geometry, translate(bounds($geometry), ("attribute1"/100)*bounds_width($geometry), 0))

• First (Bottom) layer - attribute1

  Symbol Layer Type: Simple Fill

Note that the expression for each layer uses the attribute for the previous layer.

My attribute values are whole number percentage values (eg 20% is stored as 20). If yours are decimals (eg 20% is stored as 0.2), substitute the attribute name "attribute1" instead of ("attribute1"/100) in the expressions provided.