diff options
Diffstat (limited to 'src/python/gudhi/cubical_complex.pyx')
| -rw-r--r-- | src/python/gudhi/cubical_complex.pyx | 30 |
1 files changed, 30 insertions, 0 deletions
diff --git a/src/python/gudhi/cubical_complex.pyx b/src/python/gudhi/cubical_complex.pyx index 007abcb6..69d0f0b6 100644 --- a/src/python/gudhi/cubical_complex.pyx +++ b/src/python/gudhi/cubical_complex.pyx @@ -37,6 +37,7 @@ cdef extern from "Persistent_cohomology_interface.h" namespace "Gudhi": Cubical_complex_persistence_interface(Bitmap_cubical_complex_base_interface * st, bool persistence_dim_max) void compute_persistence(int homology_coeff_field, double min_persistence) vector[pair[int, pair[double, double]]] get_persistence() + vector[vector[int]] cofaces_of_cubical_persistence_pairs() vector[int] betti_numbers() vector[int] persistent_betti_numbers(double from_value, double to_value) vector[pair[double,double]] intervals_in_dimension(int dimension) @@ -170,6 +171,35 @@ cdef class CubicalComplex: self.compute_persistence(homology_coeff_field, min_persistence) return self.pcohptr.get_persistence() + def cofaces_of_persistence_pairs(self): + """A persistence interval is described by a pair of cells, one that creates the + feature and one that kills it. The filtration values of those 2 cells give coordinates + for a point in a persistence diagram, or a bar in a barcode. Structurally, in the + cubical complexes provided here, the filtration value of any cell is the minimum of the + filtration values of the maximal cells that contain it. Connecting persistence diagram + coordinates to the corresponding value in the input (i.e. the filtration values of + the top-dimensional cells) is useful for differentiation purposes. + + This function returns a list of pairs of top-dimensional cells corresponding to + the persistence birth and death cells of the filtration. The cells are represented by + their indices in the input list of top-dimensional cells (and not their indices in the + internal datastructure that includes non-maximal cells). Note that when two adjacent + top-dimensional cells have the same filtration value, we arbitrarily return one of the two + when calling the function on one of their common faces. + + :returns: The top-dimensional cells/cofaces of the positive and negative cells, together with the corresponding homological dimension. + :rtype: numpy array of integers of shape [number_of_persistence_points, 3], the integers of eah row being: (homological dimension, + index of positive top-dimensional cell, index of negative top-dimensional cell). If the homological feature is essential, i.e., if + the death time is +infinity, then the index of the corresponding negative top-dimensional cell is -1. + """ + cdef vector[vector[int]] persistence_result + if self.pcohptr != NULL: + persistence_result = self.pcohptr.cofaces_of_cubical_persistence_pairs() + else: + print("cofaces_of_persistence_pairs function requires persistence function" + " to be launched first.") + return np.array(persistence_result) + def betti_numbers(self): """This function returns the Betti numbers of the complex. |