Module: Tsuga::Model::Cluster::ClassMethods

Defined in:
lib/tsuga/model/cluster.rb

Instance Method Summary collapse

Instance Method Details

#build_from(depth, other) ⇒ Object

Cluster factory. other is either a Cluster or a Record

FIXME: there’s a potential for overflow here on large datasets on the sum- and sum-of-squares fields. it can be mitigated by using double-precision fields, or calculating sums only on the children (instead of the subtree)



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# File 'lib/tsuga/model/cluster.rb', line 97

def build_from(depth, other)
  c = new()
  c.depth = depth

  c.lat           = other.lat
  c.lng           = other.lng
  c.children_ids  = [other.id]
  c.children_type = other.class.name

  case other
  when Cluster
    c.weight      = other.weight
    c.sum_lng     = other.sum_lng
    c.sum_lat     = other.sum_lat
    c.ssq_lng     = other.ssq_lng
    c.ssq_lat     = other.ssq_lat
  else
    c.weight      = 1
    c.sum_lng     = other.lng
    c.sum_lat     = other.lat
    c.ssq_lng     = other.lng ** 2
    c.ssq_lat     = other.lat ** 2
  end

  c.geohash # force geohash calculation
  return c
end