map_scale_electorates = {
const access_values = map_data_electorates.features.filter(f => f.properties.AREASQKM > 0 && f.properties.places_per_student).map(f => Number.parseFloat(f.properties.places_per_student));
const extent = d3.extent(access_values);
return d3.scaleDiverging()
.domain([extent[0], extent[1] / 2, extent[1]])
.interpolator(d3.interpolateRdBu)
.clamp(true);
}