the bivariate choropleth

Two things at once on one map, blended into a single colour per area.

What it leaves outAlmost nobody can read the blended colours without the key, and the two-hue scheme is hard for colour-blind readers.

3 · geospatial · geo · rung 3 · what’s related

Slocum · Axis Maps · shipped on the platform · GeoJsonLayer, two-channel fill -- no shape yet

Two worked examples

Two things at once, in one colour. Can you read it?

Before you lookCover the key. Write down what you think the darkest area means.

civicla_tracts_income_and_education.csv · 2,498 rows · 6 columns

what a household earns and how many adults hold a degree, neighbourhood by neighbourhood across Los Angeles County

What to look atTwo things everybody assumes move together, blended into one colour. The tracts to find are the ones where they come APART — and then cover the key and try to read it, which most people cannot.

This example draws itself with a small script. With scripting off you can still read every word on this page, and the file itself is at data/la_tracts_income_and_education.csv.

earth and spaceabsence_ca_counties_air_monitoring.csv · 58 rows · 5 columns

California counties: population, and whether anyone measures their air

What to look atBlend population with 'is anyone measuring'. The counties that come out dark on one axis and empty on the other are the finding.

This example draws itself with a small script. With scripting off you can still read every word on this page, and the file itself is at data/absence_ca_counties_air_monitoring.csv.

the pool

Now build one yourself.

The pool opens with this file and this shape already drawn, so your first move is to change something rather than to start from nothing. Bring your own CSV if you have one. Nothing is uploaded anywhere — the chart is drawn in your browser, your work saves there, and it downloads as a picture or as a project file you can open again.

Open the pool → the bivariate choropleth · la_tracts_income_and_education.csv