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DynamicTimeWarp.cpp
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34
35/* Author: Dave Coleman
36 */
37
38#include <ompl/tools/lightning/DynamicTimeWarp.h>
39
40#include <utility>
41
42namespace // anonymous
43{
47 inline double min3(double n1, double n2, double n3)
48 {
49 return std::min(n1, std::min(n2, n3));
50 }
51} // namespace
52
53ompl::tools::DynamicTimeWarp::DynamicTimeWarp(base::SpaceInformationPtr si) : si_(std::move(si)), table_(1, 1)
54{
55 table_(0, 0) = 0.;
56}
57
59 const og::PathGeometric &path2) const
60{
61 // Get lengths
62 std::size_t n = path1.getStateCount();
63 std::size_t m = path2.getStateCount();
64 std::size_t nrows = table_.rows(), ncols = table_.cols();
65
66 // Intialize table
67 if (nrows <= n || ncols <= m)
68 {
69 table_.resize(n + 1, m + 1);
70 for (std::size_t i = nrows; i <= n; ++i)
71 table_(i, 0) = std::numeric_limits<double>::infinity();
72 for (std::size_t i = ncols; i <= m; ++i)
73 table_(0, i) = std::numeric_limits<double>::infinity();
74 }
75
76 // Do calculations
77 double cost;
78 for (std::size_t i = 1; i <= n; ++i)
79 for (std::size_t j = 1; j <= m; ++j)
80 {
81 cost = si_->distance(path1.getState(i - 1), path2.getState(j - 1));
82 table_(i, j) = cost + min3(table_(i - 1, j), table_(i, j - 1), table_(i - 1, j - 1));
83 }
84
85 return table_(n, m);
86}
87
89{
90 // Copy the path but not the states
91 og::PathGeometric newPath1 = path1;
92 og::PathGeometric newPath2 = path2;
93
94 // Interpolate both paths so that we have an even discretization of samples
95 newPath1.interpolate();
96 newPath2.interpolate();
97
98 // compute the DTW between two vectors and divide by total path length of the longer path
99 double max_states = std::max(newPath1.getStateCount(), newPath2.getStateCount());
100
101 // Prevent division by zero
102 if (max_states == 0)
103 return std::numeric_limits<double>::max(); // the worse score possible
104
105 return calcDTWDistance(newPath1, newPath2) / max_states;
106}
Definition of a geometric path.
Definition: PathGeometric.h:66
std::size_t getStateCount() const
Get the number of states (way-points) that make up this path.
void interpolate(unsigned int count)
Insert a number of states in a path so that the path is made up of exactly count states....
base::State * getState(unsigned int index)
Get the state located at index along the path.
double getPathsScore(const og::PathGeometric &path1, const og::PathGeometric &path2) const
Use dynamic time warping to compare the similarity of two paths Note: this will interpolate both of t...
double calcDTWDistance(const og::PathGeometric &path1, const og::PathGeometric &path2) const
Use Dynamic Timewarping to score two paths.
STL namespace.