From 1e5d0ca3f84f1e5c132014d3cfc96bfe0aa3d7ee Mon Sep 17 00:00:00 2001 From: Marc Glisse Date: Sat, 9 Nov 2019 21:41:06 +0100 Subject: Empty complexes have 0 (not -1) Betti numbers --- src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h | 8 ++++++-- src/Persistent_cohomology/test/betti_numbers_unit_test.cpp | 9 +++++++++ 2 files changed, 15 insertions(+), 2 deletions(-) diff --git a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h index 944b6d35..0f1876d0 100644 --- a/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h +++ b/src/Persistent_cohomology/include/gudhi/Persistent_cohomology.h @@ -600,8 +600,10 @@ class Persistent_cohomology { * @return A vector of Betti numbers. */ std::vector betti_numbers() const { + // Don't allocate a vector of negative size for an empty complex + int siz = std::max(dim_max_, 0); // Init Betti numbers vector with zeros until Simplicial complex dimension - std::vector betti_numbers(dim_max_, 0); + std::vector betti_numbers(siz); for (auto pair : persistent_pairs_) { // Count never ended persistence intervals @@ -639,8 +641,10 @@ class Persistent_cohomology { * @return A vector of persistent Betti numbers. */ std::vector persistent_betti_numbers(Filtration_value from, Filtration_value to) const { + // Don't allocate a vector of negative size for an empty complex + int siz = std::max(dim_max_, 0); // Init Betti numbers vector with zeros until Simplicial complex dimension - std::vector betti_numbers(dim_max_, 0); + std::vector betti_numbers(siz); for (auto pair : persistent_pairs_) { // Count persistence intervals that covers the given interval // null_simplex test : if the function is called with to=+infinity, we still get something useful. And it will diff --git a/src/Persistent_cohomology/test/betti_numbers_unit_test.cpp b/src/Persistent_cohomology/test/betti_numbers_unit_test.cpp index 0a08d200..b9f11607 100644 --- a/src/Persistent_cohomology/test/betti_numbers_unit_test.cpp +++ b/src/Persistent_cohomology/test/betti_numbers_unit_test.cpp @@ -284,4 +284,13 @@ BOOST_AUTO_TEST_CASE( betti_numbers ) auto intervals_in_dimension_2 = pcoh.intervals_in_dimension(2); std::cout << "intervals_in_dimension_2.size() = " << intervals_in_dimension_2.size() << std::endl; BOOST_CHECK(intervals_in_dimension_2.size() == 0); + + std::cout << "EMPTY COMPLEX" << std::endl; + Simplex_tree empty; + empty.initialize_filtration(); + St_persistence pcoh_empty(empty, false); + pcoh_empty.init_coefficients(2); + pcoh_empty.compute_persistent_cohomology(); + BOOST_CHECK(pcoh_empty.betti_numbers().size() == 0); + BOOST_CHECK(pcoh_empty.persistent_betti_numbers(0,1).size() == 0); } -- cgit v1.2.3