Maps

Geographic grid-aggregation map

Aggregates spatial observations within a regular geographic grid.

What it answers

How do regular spatial areas compare?

The question

How are store visits spread across the country in even squares?

The country is split into equal squares coloured by store visits, darkest navy for fewest and bright cyan for most. Visits cluster in the south-east.

Illustrative data. It belongs to no company.

Spatial aggregation on a declared regular grid.

Incompatible cell areas or confusing counts with density.

Read each cell's extent and aggregate value.

Specify coordinate system, cell size and aggregation.

Layout: Long table
Fields: LocationID: text; Longitude,Latitude: numbers; Value: nonnegative number
One row is: One point location and its value or weight. What is the grain?
Rules: State CRS. For WGS84, longitude is [-180,180] and latitude [-90,90]. Validate coordinate order.
Optional: For unweighted density, each point may have weight 1. Project coordinates appropriately for distance calculations.
Preparation: Validate the input grain and missing values. State CRS. For WGS84, longitude is [-180,180] and latitude [-90,90]. Validate coordinate order.
Units: State cell area and aggregate. Counts and per-area density have different denominators.

A long table: one row per observation, few columns. New data adds rows.

Equal-area cells contain 12 and 6 events. Counts differ twofold; if cell areas differ, compute density before comparing.

LocationID	Longitude	Latitude	Value
A	18.07	59.33	30
B	11.97	57.71	45