12345qiupeng
/
gtsam
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
gtsam/gtsam/discrete/DecisionTree-inl.h

681 lines
24 KiB
C++
Raw Blame History

/* ----------------------------------------------------------------------------
* GTSAM Copyright 2010, Georgia Tech Research Corporation,
* Atlanta, Georgia 30332-0415
* All Rights Reserved
* Authors: Frank Dellaert, et al. (see THANKS for the full author list)
* See LICENSE for the license information
* -------------------------------------------------------------------------- */
/**
* @file DecisionTree.h
* @brief Decision Tree for use in DiscreteFactors
* @author Frank Dellaert
* @author Can Erdogan
* @date Jan 30, 2012
*/
#pragma once
#include <gtsam/discrete/DecisionTree.h>
#include <gtsam/base/Testable.h>
#include <boost/format.hpp>
#include <boost/optional.hpp>
#include <boost/tuple/tuple.hpp>
#include <boost/assign/std/vector.hpp>
using boost::assign::operator+=;
#include <boost/unordered_set.hpp>
#include <boost/noncopyable.hpp>
#include <list>
#include <cmath>
#include <fstream>
#include <sstream>
namespace gtsam {
/*********************************************************************************/
// Node
/*********************************************************************************/
#ifdef DT_DEBUG_MEMORY
template<typename L, typename Y>
int DecisionTree<L, Y>::Node::nrNodes = 0;
#endif
/*********************************************************************************/
// Leaf
/*********************************************************************************/
template<typename L, typename Y>
class DecisionTree<L, Y>::Leaf: public DecisionTree<L, Y>::Node {
/** constant stored in this leaf */
Y constant_;
public:
/** Constructor from constant */
Leaf(const Y& constant) :
constant_(constant) {}
/** return the constant */
const Y& constant() const {
return constant_;
}
/// Leaf-Leaf equality
bool sameLeaf(const Leaf& q) const override {
return constant_ == q.constant_;
}
/// polymorphic equality: is q is a leaf, could be
bool sameLeaf(const Node& q) const override {
return (q.isLeaf() && q.sameLeaf(*this));
}
/** equality up to tolerance */
bool equals(const Node& q, double tol) const override {
const Leaf* other = dynamic_cast<const Leaf*> (&q);
if (!other) return false;
return std::abs(double(this->constant_ - other->constant_)) < tol;
}
/** print */
void print(const std::string& s) const override {
bool showZero = true;
if (showZero || constant_) std::cout << s << " Leaf " << constant_ << std::endl;
}
/** to graphviz file */
void dot(std::ostream& os, bool showZero) const override {
if (showZero || constant_) os << "\"" << this->id() << "\" [label=\""
<< boost::format("%4.2g") % constant_
<< "\", shape=box, rank=sink, height=0.35, fixedsize=true]\n"; // width=0.55,
}
/** evaluate */
const Y& operator()(const Assignment<L>& x) const override {
return constant_;
}
/** apply unary operator */
NodePtr apply(const Unary& op) const override {
NodePtr f(new Leaf(op(constant_)));
return f;
}
// Apply binary operator "h = f op g" on Leaf node
// Note op is not assumed commutative so we need to keep track of order
// Simply calls apply on argument to call correct virtual method:
// fL.apply_f_op_g(gL) -> gL.apply_g_op_fL(fL) (below)
// fL.apply_f_op_g(gC) -> gC.apply_g_op_fL(fL) (Choice)
NodePtr apply_f_op_g(const Node& g, const Binary& op) const override {
return g.apply_g_op_fL(*this, op);
}
// Applying binary operator to two leaves results in a leaf
NodePtr apply_g_op_fL(const Leaf& fL, const Binary& op) const override {
NodePtr h(new Leaf(op(fL.constant_, constant_))); // fL op gL
return h;
}
// If second argument is a Choice node, call it's apply with leaf as second
NodePtr apply_g_op_fC(const Choice& fC, const Binary& op) const override {
return fC.apply_fC_op_gL(*this, op); // operand order back to normal
}
/** choose a branch, create new memory ! */
NodePtr choose(const L& label, size_t index) const override {
return NodePtr(new Leaf(constant()));
}
bool isLeaf() const override { return true; }
}; // Leaf
/*********************************************************************************/
// Choice
/*********************************************************************************/
template<typename L, typename Y>
class DecisionTree<L, Y>::Choice: public DecisionTree<L, Y>::Node {
/** the label of the variable on which we split */
L label_;
/** The children of this Choice node. */
std::vector<NodePtr> branches_;
private:
/** incremental allSame */
size_t allSame_;
typedef boost::shared_ptr<const Choice> ChoicePtr;
public:
virtual ~Choice() {
#ifdef DT_DEBUG_MEMORY
std::std::cout << Node::nrNodes << " destructing (Choice) " << this->id() << std::std::endl;
#endif
}
/** If all branches of a choice node f are the same, just return a branch */
static NodePtr Unique(const ChoicePtr& f) {
#ifndef DT_NO_PRUNING
if (f->allSame_) {
assert(f->branches().size() > 0);
NodePtr f0 = f->branches_[0];
assert(f0->isLeaf());
NodePtr newLeaf(new Leaf(boost::dynamic_pointer_cast<const Leaf>(f0)->constant()));
return newLeaf;
} else
#endif
return f;
}
bool isLeaf() const override { return false; }
/** Constructor, given choice label and mandatory expected branch count */
Choice(const L& label, size_t count) :
label_(label), allSame_(true) {
branches_.reserve(count);
}
/**
* Construct from applying binary op to two Choice nodes
*/
Choice(const Choice& f, const Choice& g, const Binary& op) :
allSame_(true) {
// Choose what to do based on label
if (f.label() > g.label()) {
// f higher than g
label_ = f.label();
size_t count = f.nrChoices();
branches_.reserve(count);
for (size_t i = 0; i < count; i++)
push_back(f.branches_[i]->apply_f_op_g(g, op));
} else if (g.label() > f.label()) {
// f lower than g
label_ = g.label();
size_t count = g.nrChoices();
branches_.reserve(count);
for (size_t i = 0; i < count; i++)
push_back(g.branches_[i]->apply_g_op_fC(f, op));
} else {
// f same level as g
label_ = f.label();
size_t count = f.nrChoices();
branches_.reserve(count);
for (size_t i = 0; i < count; i++)
push_back(f.branches_[i]->apply_f_op_g(*g.branches_[i], op));
}
}
const L& label() const {
return label_;
}
size_t nrChoices() const {
return branches_.size();
}
const std::vector<NodePtr>& branches() const {
return branches_;
}
/** add a branch: TODO merge into constructor */
void push_back(const NodePtr& node) {
// allSame_ is restricted to leaf nodes in a decision tree
if (allSame_ && !branches_.empty()) {
allSame_ = node->sameLeaf(*branches_.back());
}
branches_.push_back(node);
}
/** print (as a tree) */
void print(const std::string& s) const override {
std::cout << s << " Choice(";
// std::cout << this << ",";
std::cout << label_ << ") " << std::endl;
for (size_t i = 0; i < branches_.size(); i++)
branches_[i]->print((boost::format("%s %d") % s % i).str());
}
/** output to graphviz (as a a graph) */
void dot(std::ostream& os, bool showZero) const override {
os << "\"" << this->id() << "\" [shape=circle, label=\"" << label_
<< "\"]\n";
for (size_t i = 0; i < branches_.size(); i++) {
NodePtr branch = branches_[i];
// Check if zero
if (!showZero) {
const Leaf* leaf = dynamic_cast<const Leaf*> (branch.get());
if (leaf && !leaf->constant()) continue;
}
os << "\"" << this->id() << "\" -> \"" << branch->id() << "\"";
if (i == 0) os << " [style=dashed]";
if (i > 1) os << " [style=bold]";
os << std::endl;
branch->dot(os, showZero);
}
}
/// Choice-Leaf equality: always false
bool sameLeaf(const Leaf& q) const override {
return false;
}
/// polymorphic equality: if q is a leaf, could be...
bool sameLeaf(const Node& q) const override {
return (q.isLeaf() && q.sameLeaf(*this));
}
/** equality up to tolerance */
bool equals(const Node& q, double tol) const override {
const Choice* other = dynamic_cast<const Choice*> (&q);
if (!other) return false;
if (this->label_ != other->label_) return false;
if (branches_.size() != other->branches_.size()) return false;
// we don't care about shared pointers being equal here
for (size_t i = 0; i < branches_.size(); i++)
if (!(branches_[i]->equals(*(other->branches_[i]), tol))) return false;
return true;
}
/** evaluate */
const Y& operator()(const Assignment<L>& x) const override {
#ifndef NDEBUG
typename Assignment<L>::const_iterator it = x.find(label_);
if (it == x.end()) {
std::cout << "Trying to find value for " << label_ << std::endl;
throw std::invalid_argument(
"DecisionTree::operator(): value undefined for a label");
}
#endif
size_t index = x.at(label_);
NodePtr child = branches_[index];
return (*child)(x);
}
/**
* Construct from applying unary op to a Choice node
*/
Choice(const L& label, const Choice& f, const Unary& op) :
label_(label), allSame_(true) {
branches_.reserve(f.branches_.size()); // reserve space
for (const NodePtr& branch: f.branches_)
push_back(branch->apply(op));
}
/** apply unary operator */
NodePtr apply(const Unary& op) const override {
boost::shared_ptr<Choice> r(new Choice(label_, *this, op));
return Unique(r);
}
// Apply binary operator "h = f op g" on Choice node
// Note op is not assumed commutative so we need to keep track of order
// Simply calls apply on argument to call correct virtual method:
// fC.apply_f_op_g(gL) -> gL.apply_g_op_fC(fC) -> (Leaf)
// fC.apply_f_op_g(gC) -> gC.apply_g_op_fC(fC) -> (below)
NodePtr apply_f_op_g(const Node& g, const Binary& op) const override {
return g.apply_g_op_fC(*this, op);
}
// If second argument of binary op is Leaf node, recurse on branches
NodePtr apply_g_op_fL(const Leaf& fL, const Binary& op) const override {
boost::shared_ptr<Choice> h(new Choice(label(), nrChoices()));
for(NodePtr branch: branches_)
h->push_back(fL.apply_f_op_g(*branch, op));
return Unique(h);
}
// If second argument of binary op is Choice, call constructor
NodePtr apply_g_op_fC(const Choice& fC, const Binary& op) const override {
boost::shared_ptr<Choice> h(new Choice(fC, *this, op));
return Unique(h);
}
// If second argument of binary op is Leaf
template<typename OP>
NodePtr apply_fC_op_gL(const Leaf& gL, OP op) const {
boost::shared_ptr<Choice> h(new Choice(label(), nrChoices()));
for(const NodePtr& branch: branches_)
h->push_back(branch->apply_f_op_g(gL, op));
return Unique(h);
}
/** choose a branch, recursively */
NodePtr choose(const L& label, size_t index) const override {
if (label_ == label)
return branches_[index]; // choose branch
// second case, not label of interest, just recurse
boost::shared_ptr<Choice> r(new Choice(label_, branches_.size()));
for(const NodePtr& branch: branches_)
r->push_back(branch->choose(label, index));
return Unique(r);
}
}; // Choice
/*********************************************************************************/
// DecisionTree
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree() {
}
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree(const NodePtr& root) :
root_(root) {
}
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree(const Y& y) {
root_ = NodePtr(new Leaf(y));
}
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree(//
const L& label, const Y& y1, const Y& y2) {
boost::shared_ptr<Choice> a(new Choice(label, 2));
NodePtr l1(new Leaf(y1)), l2(new Leaf(y2));
a->push_back(l1);
a->push_back(l2);
root_ = Choice::Unique(a);
}
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree(//
const LabelC& labelC, const Y& y1, const Y& y2) {
if (labelC.second != 2) throw std::invalid_argument(
"DecisionTree: binary constructor called with non-binary label");
boost::shared_ptr<Choice> a(new Choice(labelC.first, 2));
NodePtr l1(new Leaf(y1)), l2(new Leaf(y2));
a->push_back(l1);
a->push_back(l2);
root_ = Choice::Unique(a);
}
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree(const std::vector<LabelC>& labelCs,
const std::vector<Y>& ys) {
// call recursive Create
root_ = create(labelCs.begin(), labelCs.end(), ys.begin(), ys.end());
}
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree(const std::vector<LabelC>& labelCs,
const std::string& table) {
// Convert std::string to values of type Y
std::vector<Y> ys;
std::istringstream iss(table);
copy(std::istream_iterator<Y>(iss), std::istream_iterator<Y>(),
back_inserter(ys));
// now call recursive Create
root_ = create(labelCs.begin(), labelCs.end(), ys.begin(), ys.end());
}
/*********************************************************************************/
template<typename L, typename Y>
template<typename Iterator> DecisionTree<L, Y>::DecisionTree(
Iterator begin, Iterator end, const L& label) {
root_ = compose(begin, end, label);
}
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y>::DecisionTree(const L& label,
const DecisionTree& f0, const DecisionTree& f1) {
std::vector<DecisionTree> functions;
functions += f0, f1;
root_ = compose(functions.begin(), functions.end(), label);
}
/*********************************************************************************/
template<typename L, typename Y>
template<typename M, typename X>
DecisionTree<L, Y>::DecisionTree(const DecisionTree<M, X>& other,
const std::map<M, L>& map, boost::function<Y(const X&)> op) {
root_ = convert(other.root_, map, op);
}
/*********************************************************************************/
// Called by two constructors above.
// Takes a label and a corresponding range of decision trees, and creates a new
// decision tree. However, the order of the labels needs to be respected, so we
// cannot just create a root Choice node on the label: if the label is not the
// highest label, we need to do a complicated and expensive recursive call.
template<typename L, typename Y> template<typename Iterator>
typename DecisionTree<L, Y>::NodePtr DecisionTree<L, Y>::compose(Iterator begin,
Iterator end, const L& label) const {
// find highest label among branches
boost::optional<L> highestLabel;
size_t nrChoices = 0;
for (Iterator it = begin; it != end; it++) {
if (it->root_->isLeaf())
continue;
boost::shared_ptr<const Choice> c =
boost::dynamic_pointer_cast<const Choice>(it->root_);
if (!highestLabel || c->label() > *highestLabel) {
highestLabel.reset(c->label());
nrChoices = c->nrChoices();
}
}
// if label is already in correct order, just put together a choice on label
if (!nrChoices || !highestLabel || label > *highestLabel) {
boost::shared_ptr<Choice> choiceOnLabel(new Choice(label, end - begin));
for (Iterator it = begin; it != end; it++)
choiceOnLabel->push_back(it->root_);
return Choice::Unique(choiceOnLabel);
} else {
// Set up a new choice on the highest label
boost::shared_ptr<Choice> choiceOnHighestLabel(new Choice(*highestLabel, nrChoices));
// now, for all possible values of highestLabel
for (size_t index = 0; index < nrChoices; index++) {
// make a new set of functions for composing by iterating over the given
// functions, and selecting the appropriate branch.
std::vector<DecisionTree> functions;
for (Iterator it = begin; it != end; it++) {
// by restricting the input functions to value i for labelBelow
DecisionTree chosen = it->choose(*highestLabel, index);
functions.push_back(chosen);
}
// We then recurse, for all values of the highest label
NodePtr fi = compose(functions.begin(), functions.end(), label);
choiceOnHighestLabel->push_back(fi);
}
return Choice::Unique(choiceOnHighestLabel);
}
}
/*********************************************************************************/
// "create" is a bit of a complicated thing, but very useful.
// It takes a range of labels and a corresponding range of values,
// and creates a decision tree, as follows:
// - if there is only one label, creates a choice node with values in leaves
// - otherwise, it evenly splits up the range of values and creates a tree for
// each sub-range, and assigns that tree to first label's choices
// Example:
// create([B A],[1 2 3 4]) would call
// create([A],[1 2])
// create([A],[3 4])
// and produce
// B=0
// A=0: 1
// A=1: 2
// B=1
// A=0: 3
// A=1: 4
// Note, through the magic of "compose", create([A B],[1 2 3 4]) will produce
// exactly the same tree as above: the highest label is always the root.
// However, it will be *way* faster if labels are given highest to lowest.
template<typename L, typename Y>
template<typename It, typename ValueIt>
typename DecisionTree<L, Y>::NodePtr DecisionTree<L, Y>::create(
It begin, It end, ValueIt beginY, ValueIt endY) const {
// get crucial counts
size_t nrChoices = begin->second;
size_t size = endY - beginY;
// Find the next key to work on
It labelC = begin + 1;
if (labelC == end) {
// Base case: only one key left
// Create a simple choice node with values as leaves.
if (size != nrChoices) {
std::cout << "Trying to create DD on " << begin->first << std::endl;
std::cout << boost::format("DecisionTree::create: expected %d values but got %d instead") % nrChoices % size << std::endl;
throw std::invalid_argument("DecisionTree::create invalid argument");
}
boost::shared_ptr<Choice> choice(new Choice(begin->first, endY - beginY));
for (ValueIt y = beginY; y != endY; y++)
choice->push_back(NodePtr(new Leaf(*y)));
return Choice::Unique(choice);
}
// Recursive case: perform "Shannon expansion"
// Creates one tree (i.e.,function) for each choice of current key
// by calling create recursively, and then puts them all together.
std::vector<DecisionTree> functions;
size_t split = size / nrChoices;
for (size_t i = 0; i < nrChoices; i++, beginY += split) {
NodePtr f = create<It, ValueIt>(labelC, end, beginY, beginY + split);
functions += DecisionTree(f);
}
return compose(functions.begin(), functions.end(), begin->first);
}
/*********************************************************************************/
template<typename L, typename Y>
template<typename M, typename X>
typename DecisionTree<L, Y>::NodePtr DecisionTree<L, Y>::convert(
const typename DecisionTree<M, X>::NodePtr& f, const std::map<M, L>& map,
boost::function<Y(const X&)> op) {
typedef DecisionTree<M, X> MX;
typedef typename MX::Leaf MXLeaf;
typedef typename MX::Choice MXChoice;
typedef typename MX::NodePtr MXNodePtr;
typedef DecisionTree<L, Y> LY;
// ugliness below because apparently we can't have templated virtual functions
// If leaf, apply unary conversion "op" and create a unique leaf
const MXLeaf* leaf = dynamic_cast<const MXLeaf*> (f.get());
if (leaf) return NodePtr(new Leaf(op(leaf->constant())));
// Check if Choice
boost::shared_ptr<const MXChoice> choice = boost::dynamic_pointer_cast<const MXChoice> (f);
if (!choice) throw std::invalid_argument(
"DecisionTree::Convert: Invalid NodePtr");
// get new label
M oldLabel = choice->label();
L newLabel = map.at(oldLabel);
// put together via Shannon expansion otherwise not sorted.
std::vector<LY> functions;
for(const MXNodePtr& branch: choice->branches()) {
LY converted(convert<M, X>(branch, map, op));
functions += converted;
}
return LY::compose(functions.begin(), functions.end(), newLabel);
}
/*********************************************************************************/
template<typename L, typename Y>
bool DecisionTree<L, Y>::equals(const DecisionTree& other, double tol) const {
return root_->equals(*other.root_, tol);
}
template<typename L, typename Y>
void DecisionTree<L, Y>::print(const std::string& s) const {
root_->print(s);
}
template<typename L, typename Y>
bool DecisionTree<L, Y>::operator==(const DecisionTree& other) const {
return root_->equals(*other.root_);
}
template<typename L, typename Y>
const Y& DecisionTree<L, Y>::operator()(const Assignment<L>& x) const {
return root_->operator ()(x);
}
template<typename L, typename Y>
DecisionTree<L, Y> DecisionTree<L, Y>::apply(const Unary& op) const {
return DecisionTree(root_->apply(op));
}
/*********************************************************************************/
template<typename L, typename Y>
DecisionTree<L, Y> DecisionTree<L, Y>::apply(const DecisionTree& g,
const Binary& op) const {
// apply the operaton on the root of both diagrams
NodePtr h = root_->apply_f_op_g(*g.root_, op);
// create a new class with the resulting root "h"
DecisionTree result(h);
return result;
}
/*********************************************************************************/
// The way this works:
// We have an ADT, picture it as a tree.
// At a certain depth, we have a branch on "label".
// The function "choose(label,index)" will return a tree of one less depth,
// where there is no more branch on "label": only the subtree under that
// branch point corresponding to the value "index" is left instead.
// The function below get all these smaller trees and "ops" them together.
// This implements marginalization in Darwiche09book, pg 330
template<typename L, typename Y>
DecisionTree<L, Y> DecisionTree<L, Y>::combine(const L& label,
size_t cardinality, const Binary& op) const {
DecisionTree result = choose(label, 0);
for (size_t index = 1; index < cardinality; index++) {
DecisionTree chosen = choose(label, index);
result = result.apply(chosen, op);
}
return result;
}
/*********************************************************************************/
template<typename L, typename Y>
void DecisionTree<L, Y>::dot(std::ostream& os, bool showZero) const {
os << "digraph G {\n";
root_->dot(os, showZero);
os << " [ordering=out]}" << std::endl;
}
template<typename L, typename Y>
void DecisionTree<L, Y>::dot(const std::string& name, bool showZero) const {
std::ofstream os((name + ".dot").c_str());
dot(os, showZero);
int result = system(
("dot -Tpdf " + name + ".dot -o " + name + ".pdf >& /dev/null").c_str());
if (result==-1) throw std::runtime_error("DecisionTree::dot system call failed");
}
/*********************************************************************************/
} // namespace gtsam
Reference in New Issue View Git Blame Copy Permalink