classify

⚠️ This repository is no longer maintained by Lukas Martinelli.

A YAML format for classification of single values. The classify.py Python program will produce a classification function for various language targets for the given YAML format.

This approach is used in osm2vectortiles where we categorize OpenStreetMap values into different feature classes and icons.

Get started

You need to have Python 2 or Python 3 installed on your system.

git clone https://github.com/lukasmartinelli/classify.git
cd classify
pip install -r requirements.txt

# generate sql code
./classify.py sql <yaml-definition>

# generate python code
./classify.py python <yaml-definition>

Example

Map the value of a OpenStreetMap tag into a feature_class. This enables map designers to style several map features at once (e.g. the main roads instead of alot of individual road types).

Create a new file feature_class.yml and name your classification system. Then you need to list all classes you want to reduce (street, main, driveway). For each class you define a list of values that you want to map to your class.

system:
  name: feature_class
  classes:
    street:
    - residential
    - unclassified
    - living_street
    - road
    - raceway
    main:
    - primary
    - primary_link
    - trunk
    - trunk_link
    - secondary
    - secondary_link
    - tertiary
    - tertiary_link
    driveway:
    - driveway

Generated SQL.

CREATE OR REPLACE FUNCTION classify_osm_feature_class(type VARCHAR)
  RETURNS VARCHAR AS $$
  BEGIN
  RETURN CASE
    WHEN type IN ('motorway','motorway_link','driveway') THEN 'highway'
    WHEN type IN ('primary','primary_link', 'trunk', 'trunk_link',
                  'secondary','secondary_link',
                  'tertiary','tertiary_link') THEN 'main'
  END;
END;
$$ LANGUAGE plpgsql IMMUTABLE;

Structure

The system defines a classification system for values. You can give a system a name. The name of your system will appear in the generated code.

A classification system has many classes. Each class is a key (the class name) and values (the values that are matched to the class). Only text values are supported.

system:
  name: <name-classification-system>
  classes:
    <class-name>:
    - <value-to-match>