the choropleth map

Darker means more, lighter means less — one number, shaded region by region. Big regions grab the eye whether or not many people live there.

What it leaves outBig areas shout. A large empty region looks more important than a small crowded one.

3 · geospatial · geo · level 3 · compare and choose · taught in dive 3.5 · dive 4.1

Two worked examples

Which borough has the worst rat problem?

Before you lookWrite down your answer, then look at the map and write it again.

civicchoropleth_nyc_rat_complaints_by_borough.csv · 5 rows · 2 columns

rat complaints by borough

What to look atColour intensity by area. Staten Island is large and quiet; Manhattan is small and loud. Which one does the map make look important?

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/choropleth_nyc_rat_complaints_by_borough.csv.

earth and spaceabsence_ca_counties_air_monitoring.csv · 58 rows · 5 columns

median air quality in every California county

What to look atThe counties with no monitor at all are the ones to look for. An empty county is not a clean county.

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 choropleth map · choropleth_nyc_rat_complaints_by_borough.csv