bayesBall_tpl.h

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 *       - Pierre-Henri WUILLEMIN(_at_LIP6)                                 *
 *       - Christophe GONZALES(_at_AMU)                                     *
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#pragma once
 
#include <agrum/base/graphs/algorithms/generic/bayesBall.h>
 
namespace gum::graph {
 
  template < GUM_DiGraphable G, bool CollectAll >
  NodeSet
      _bayesBall_(const G& g, const NodeSet& query, const NodeSet& Zhard, const NodeSet& Zsoft) {
    NodeSet result;
 
    static constexpr std::pair< bool, bool > empty_mark{false, false};
    NodeProperty< std::pair< bool, bool > >  marks(g.size());
 
    List< std::pair< NodeId, bool > > to_visit;
    for (const auto node: query)
      to_visit.insert(std::pair{node, true});
 
    while (!to_visit.empty()) {
      const NodeId node       = to_visit.front().first;
      const bool   from_child = to_visit.front().second;
      to_visit.popFront();
 
      auto& [top, bot] = marks.getWithDefault(node, empty_mark);
 
      if (from_child) {
        result.insert(node);                // always requisite on upward visit
        if (Zhard.exists(node)) continue;   // hard evidence blocks upward
 
        if (!top) {
          top = true;
          for (const auto par: g.parents(node))
            to_visit.insert(std::pair{par, true});
        }
        if (!bot) {
          bot = true;
          for (const auto chi: g.children(node))
            to_visit.insert(std::pair{chi, false});
        }
 
      } else {
        if constexpr (CollectAll) result.insert(node);   // dConnected: all visits
 
        const bool is_hard = Zhard.exists(node);
        const bool is_ev   = is_hard || Zsoft.exists(node);
 
        if (is_ev && !top) {
          top = true;
          if constexpr (!CollectAll) result.insert(node);   // requisiteNodes: collider only
          for (const auto par: g.parents(node))
            to_visit.insert(std::pair{par, true});
        }
        if (!is_hard && !bot) {
          bot = true;
          for (const auto chi: g.children(node))
            to_visit.insert(std::pair{chi, false});
        }
      }
    }
 
    return result;
  }
 
  template < GUM_DiGraphable G >
  NodeSet
      requisiteNodes(const G& g, const NodeSet& query, const NodeSet& Zhard, const NodeSet& Zsoft) {
    return _bayesBall_< G, false >(g, query, Zhard, Zsoft);
  }
 
  template < GUM_DiGraphable G >
  NodeSet dConnected(const G& g, const NodeSet& query, const NodeSet& Zhard, const NodeSet& Zsoft) {
    return _bayesBall_< G, true >(g, query, Zhard, Zsoft);
  }
 
}   // namespace gum::graph