Module: SpatialStats::Weights::Contiguous

Defined in:
lib/spatial_stats/weights/contiguous.rb

Overview

Contiguous weights module includes methods that provide an interface to coniguous weights queries and formats the result properly to utilize a weights matrix.

Class Method Summary collapse

Class Method Details

.queen(scope, field) ⇒ WeightsMatrix

Compute queen weights matrix for a scope.

Parameters:

  • scope (ActiveRecord::Relation) —

    to query

  • field (Symbol, String) —

    with geometry in it

Returns:



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# File 'lib/spatial_stats/weights/contiguous.rb', line 47

def self.queen(scope, field)
  neighbors = SpatialStats::Queries::Weights
              .queen_contiguity_neighbors(scope, field)

  # get keys to make sure we have consistent dimensions when
  # some entries don't have neighbors.
  # define a new hash that has all the keys from scope
  keys = SpatialStats::Queries::Variables.query_field(scope, scope.klass.primary_key)

  neighbors = neighbors.group_by(&:i_id)
  missing_neighbors = Hash[(keys - neighbors.keys).map { |key| [key, []] }]
  neighbors = neighbors.merge(missing_neighbors)

  weights = neighbors.transform_values do |value|
    value.map do |neighbor|
      hash = { id: neighbor[:j_id] }
      hash[:weight] = 1
      hash
    end
  end
  SpatialStats::Weights::WeightsMatrix.new(weights)
end

.rook(scope, field) ⇒ WeightsMatrix

Compute rook weights matrix for a scope.

Parameters:

  • scope (ActiveRecord::Relation) —

    to query

  • field (Symbol, String) —

    with geometry in it

Returns:



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# File 'lib/spatial_stats/weights/contiguous.rb', line 17

def self.rook(scope, field)
  neighbors = SpatialStats::Queries::Weights
              .rook_contiguity_neighbors(scope, field)

  # get keys to make sure we have consistent dimensions when
  # some entries don't have neighbors.
  # define a new hash that has all the keys from scope
  keys = SpatialStats::Queries::Variables.query_field(scope, scope.klass.primary_key)

  neighbors = neighbors.group_by(&:i_id)
  missing_neighbors = Hash[(keys - neighbors.keys).map { |key| [key, []] }]
  neighbors = neighbors.merge(missing_neighbors)

  weights = neighbors.transform_values do |value|
    value.map do |neighbor|
      hash = { id: neighbor[:j_id] }
      hash[:weight] = 1
      hash
    end
  end
  SpatialStats::Weights::WeightsMatrix.new(weights)
end