Class: GD::GIS::Classifier

Inherits:
Object
  • Object
show all
Defined in:
lib/gd/gis/classifier.rb

Overview

Classifies geographic features based on their properties.

This class provides a set of stateless helpers used to infer semantic categories (roads, water, parks, rails) from feature attribute tags, typically originating from OpenStreetMap or similar datasets.

All methods are pure functions and return symbols or booleans suitable for styling or rendering decisions.

Class Method Summary collapse

Class Method Details

.park?(feature) ⇒ Boolean

Determines whether a feature represents a park or green area.

Parameters:

Returns:

  • (Boolean) —

    true if the feature is a park or green space



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# File 'lib/gd/gis/classifier.rb', line 72

def self.park?(feature)
  tags = feature.properties || {}
  %w[park recreation_ground garden].include?(tags["leisure"]) ||
    %w[park grass forest].include?(tags["landuse"])
end

.rail?(feature) ⇒ Boolean

Determines whether a feature represents a railway.

Parameters:

Returns:

  • (Boolean) —

    true if the feature is a rail feature



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# File 'lib/gd/gis/classifier.rb', line 63

def self.rail?(feature)
  tags = feature.properties || {}
  tags["railway"]
end

.road(feature) ⇒ Symbol?

Classifies a road feature into a road category.

The classification is based on the ‘highway` tag.

Parameters:

Returns:

  • (Symbol, nil) —

    one of:

    • :motorway

    • :primary

    • :secondary

    • :street

    • :minor

    • nil if the feature is not a road



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# File 'lib/gd/gis/classifier.rb', line 29

def self.road(feature)
  tags = feature.properties || {}

  case tags["highway"]
  when "motorway", "trunk"
    :motorway
  when "primary", "primary_link"
    :primary
  when "secondary", "secondary_link"
    :secondary
  when "tertiary", "residential", "living_street"
    :street
  when "service", "track"
    :minor
  end
end

.water?(feature) ⇒ Boolean

Determines whether a feature represents water.

Parameters:

Returns:

  • (Boolean) —

    true if the feature is water-related



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# File 'lib/gd/gis/classifier.rb', line 50

def self.water?(feature)
  p = feature.properties

  p["waterway"] ||
    p["natural"] == "water" ||
    p["fclass"] == "river" ||
    p["fclass"] == "stream"
end

.water_kind(feature) ⇒ Symbol

Classifies the type of water feature.

Parameters:

Returns:

  • (Symbol) —

    • :river

    • :stream

    • :minor (default / fallback)



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# File 'lib/gd/gis/classifier.rb', line 85

def self.water_kind(feature)
  p = feature.properties

  case p["waterway"] || p["fclass"]
  when "river"  then :river
  when "stream" then :stream
  else :minor
  end
end