The Leaflet Choropleth module provides advanced choropleth mapping capabilities
for Drupal applications, enabling the visualization of statistical data through
color-coded geographic regions. This module seamlessly integrates with the
existing Leaflet ecosystem to deliver professional-grade thematic mapping
functionality.

Installation

Composer Installation

composer require drupal/leaflet_choropleth

Module Installation

Via Drupal Admin UI:

Navigate to /admin/modules
Search for "Leaflet Choropleth"
Check the module checkbox
Click "Install"

Via Drush:

drush en leaflet_choropleth

Configuration and Usage

View Style Integration

The module provides a leaflet_choropleth_map view style plugin that
integrates seamlessly with the leaflet_map view style from the leaflet_view
submodule.
This integration adds and enables an additional "Choropleth Map Settings"
section where to configure choropleth-specific settings alongside standard
leaflet mapping options.

Usage requirements and setup

The choropleth visualization applies only to features with polygon or
multipolygon geometry types.

To enable a choropleth map for your data, follow these steps:

create a leaflet_choropleth_map view that includes Drupal content or
entities with a numeric field (integer or float) to be used as the basis for
the choropleth data visualization
in the "Choropleth Map Settings" section enable the Choroplath Map option and
set the data source to the desired numeric field
configure additional settings such as classification methods, color scale,
number of classes, geometries display options, legend configuration and other
display preferences

Classifications and Color Ranges

The module implements a robust plugin system for data classification and color
schemes:

Classification Methods:

Equal Interval: Divides data into equal-sized ranges
Geometric Interval: Creates class breaks based on geometric progression
Natural Breaks (Jenks): Optimizes class boundaries to minimize variance
Quantile: Divides data into equal-sized groups
Standard Deviation: Classes based on statistical deviation from mean
Etc: additional classification methods (custom implementations)
available through the plugin system

Color Ranges:

Sequential: Single-hue progressions (Blues, Greens, Reds, Grays)
Diverging: Two-color endpoints with neutral midpoint (Red-Blue)
Categorical: Distinct colors for categorical data
Etc: additional color ranges (custom implementations)
available through the plugin system

Legend Configuration

The module provides a configurable legend system that can be:

Added as a Leaflet Control directly within the map
Positioned anywhere on the map interface
Fully customized for styling and content
Integrated with the choropleth theming system

Theming Integration

Leaflet choropleth layers can be seamlessly integrated and mixed with existing
leaflet mapping features, allowing for:

Combining choropleth analysis with marker & geometries visualizations
Multi-layer mapping compositions, with flexible theming and styling options

Development Status

This is a first phase release of the Leaflet Choropleth module, deployed to
the Drupal community for testing and review. The module is being developed with
the intention of eventual integration into the main Leaflet module as a
leaflet_choropleth submodule once the functionality has been thoroughly
validated and consolidated by the community.

Dependencies

Leaflet module

Support

For issues, feature requests, and community support, please visit the
project page on Drupal.org.

Leaflet Choropleth

Issues

Custom Choropleth value and color rangesActiveCode Created 11 days ago

Legend missing on Page, but shown in View editActiveCode Created 14 days ago

Custom Choropleth value and color ranges
Active
Code
Created 11 days ago

Legend missing on Page, but shown in View edit
Active
Code
Created 14 days ago