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author | Marc Glisse <marc.glisse@inria.fr> | 2020-03-30 17:56:27 +0200 |
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committer | GitHub <noreply@github.com> | 2020-03-30 17:56:27 +0200 |
commit | 2f46606b406aafc69e37a68dca33e1858ab7b817 (patch) | |
tree | 00fe086be752902c58d9126e9959120f28f06406 /src/python/gudhi | |
parent | c669664a7bdda51d31410b6fa0f7c41e9e616b07 (diff) | |
parent | b2a549c055c2796fe4eb1e4e4265cdd718753416 (diff) |
Merge pull request #215 from MathieuCarriere/extended_persistence
Extended persistence
Diffstat (limited to 'src/python/gudhi')
-rw-r--r-- | src/python/gudhi/simplex_tree.pxd | 2 | ||||
-rw-r--r-- | src/python/gudhi/simplex_tree.pyx | 51 |
2 files changed, 53 insertions, 0 deletions
diff --git a/src/python/gudhi/simplex_tree.pxd b/src/python/gudhi/simplex_tree.pxd index 82f155de..595f22bb 100644 --- a/src/python/gudhi/simplex_tree.pxd +++ b/src/python/gudhi/simplex_tree.pxd @@ -57,6 +57,8 @@ cdef extern from "Simplex_tree_interface.h" namespace "Gudhi": void remove_maximal_simplex(vector[int] simplex) bool prune_above_filtration(double filtration) bool make_filtration_non_decreasing() + void compute_extended_filtration() + vector[vector[pair[int, pair[double, double]]]] compute_extended_persistence_subdiagrams(vector[pair[int, pair[double, double]]] dgm, double min_persistence) # Iterators over Simplex tree pair[vector[int], double] get_simplex_and_filtration(Simplex_tree_simplex_handle f_simplex) Simplex_tree_simplices_iterator get_simplices_iterator_begin() diff --git a/src/python/gudhi/simplex_tree.pyx b/src/python/gudhi/simplex_tree.pyx index c01cc905..cc3753e1 100644 --- a/src/python/gudhi/simplex_tree.pyx +++ b/src/python/gudhi/simplex_tree.pyx @@ -396,6 +396,57 @@ cdef class SimplexTree: """ return self.get_ptr().make_filtration_non_decreasing() + def extend_filtration(self): + """ Extend filtration for computing extended persistence. This function only uses the + filtration values at the 0-dimensional simplices, and computes the extended persistence + diagram induced by the lower-star filtration computed with these values. + + .. note:: + + Note that after calling this function, the filtration + values are actually modified within the Simplex_tree. + The function :func:`extended_persistence()<gudhi.SimplexTree.extended_persistence>` + retrieves the original values. + + .. note:: + + Note that this code creates an extra vertex internally, so you should make sure that + the Simplex_tree does not contain a vertex with the largest possible value (i.e., 4294967295). + """ + return self.get_ptr().compute_extended_filtration() + + def extended_persistence(self, homology_coeff_field=11, min_persistence=0): + """This function retrieves good values for extended persistence, and separate the diagrams + into the Ordinary, Relative, Extended+ and Extended- subdiagrams. + + :param homology_coeff_field: The homology coefficient field. Must be a + prime number. Default value is 11. + :type homology_coeff_field: int. + :param min_persistence: The minimum persistence value (i.e., the absolute value of the difference between the persistence diagram point coordinates) to take into + account (strictly greater than min_persistence). Default value is + 0.0. + Sets min_persistence to -1.0 to see all values. + :type min_persistence: float. + :returns: A list of four persistence diagrams in the format described in :func:`persistence()<gudhi.SimplexTree.persistence>`. The first one is Ordinary, the second one is Relative, the third one is Extended+ and the fourth one is Extended-. See https://link.springer.com/article/10.1007/s10208-008-9027-z and/or section 2.2 in https://link.springer.com/article/10.1007/s10208-017-9370-z for a description of these subtypes. + + .. note:: + + This function should be called only if :func:`extend_filtration()<gudhi.SimplexTree.extend_filtration>` has been called first! + + .. note:: + + The coordinates of the persistence diagram points might be a little different than the + original filtration values due to the internal transformation (scaling to [-2,-1]) that is + performed on these values during the computation of extended persistence. + """ + cdef vector[pair[int, pair[double, double]]] persistence_result + if self.pcohptr != NULL: + del self.pcohptr + self.pcohptr = new Simplex_tree_persistence_interface(self.get_ptr(), False) + persistence_result = self.pcohptr.get_persistence(homology_coeff_field, -1.) + return self.get_ptr().compute_extended_persistence_subdiagrams(persistence_result, min_persistence) + + def persistence(self, homology_coeff_field=11, min_persistence=0, persistence_dim_max = False): """This function returns the persistence of the simplicial complex. |