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diff --git a/src/Persistent_cohomology/test/betti_numbers_unit_test.cpp b/src/Persistent_cohomology/test/betti_numbers_unit_test.cpp
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+++ b/src/Persistent_cohomology/test/betti_numbers_unit_test.cpp
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+#include <iostream>
+#include <string>
+#include <algorithm>
+#include <utility> // std::pair, std::make_pair
+#include <cmath> // float comparison
+#include <limits>
+
+#define BOOST_TEST_DYN_LINK
+#define BOOST_TEST_MODULE "betti_numbers"
+#include <boost/test/unit_test.hpp>
+
+#include <gudhi/Simplex_tree.h>
+#include <gudhi/Persistent_cohomology.h>
+
+struct MiniSTOptions : Gudhi::Simplex_tree_options_full_featured {
+ // Implicitly use 0 as filtration value for all simplices
+ static const bool store_filtration = false;
+ // The persistence algorithm needs this
+ static const bool store_key = true;
+ // I have few vertices
+ typedef short Vertex_handle;
+};
+
+using Mini_simplex_tree = Gudhi::Simplex_tree<MiniSTOptions>;
+using Mini_st_persistence =
+ Gudhi::persistent_cohomology::Persistent_cohomology<Mini_simplex_tree, Gudhi::persistent_cohomology::Field_Zp>;
+
+/*
+ * Compare two intervals by dimension, then by length.
+ */
+template<class Simplicial_complex>
+struct cmp_intervals_by_dim_then_length {
+ explicit cmp_intervals_by_dim_then_length(Simplicial_complex * sc)
+ : sc_(sc) { }
+
+ template<typename Persistent_interval>
+ bool operator()(const Persistent_interval & p1, const Persistent_interval & p2) {
+ if (sc_->dimension(get < 0 > (p1)) == sc_->dimension(get < 0 > (p2)))
+ return (sc_->filtration(get < 1 > (p1)) - sc_->filtration(get < 0 > (p1))
+ > sc_->filtration(get < 1 > (p2)) - sc_->filtration(get < 0 > (p2)));
+ else
+ return (sc_->dimension(get < 0 > (p1)) > sc_->dimension(get < 0 > (p2)));
+ }
+ Simplicial_complex* sc_;
+};
+
+BOOST_AUTO_TEST_CASE( plain_homology_betti_numbers )
+{
+ Mini_simplex_tree st;
+
+ /* Complex to build. */
+ /* 1 4 */
+ /* o---o */
+ /* /3\ / */
+ /* o---o o */
+ /* 2 0 5 */
+ const short tetra0123[] = {0, 1, 2, 3};
+ const short edge04[] = {0, 4};
+ const short edge14[] = {1, 4};
+ const short vertex5[] = {5};
+ st.insert_simplex_and_subfaces(tetra0123);
+ st.insert_simplex_and_subfaces(edge04);
+ st.insert_simplex(edge14);
+ st.insert_simplex(vertex5);
+
+ // Sort the simplices in the order of the filtration
+ st.initialize_filtration();
+
+ // Class for homology computation
+ Mini_st_persistence pcoh(st);
+
+ // Initialize the coefficient field Z/3Z for homology
+ pcoh.init_coefficients(3);
+
+ // Compute the persistence diagram of the complex
+ pcoh.compute_persistent_cohomology();
+
+ // Print the result. The format is, on each line: 2 dim 0 inf
+ // where 2 represents the field, dim the dimension of the feature.
+ // 2 0 0 inf
+ // 2 0 0 inf
+ // 2 1 0 inf
+ // means that in Z/2Z-homology, the Betti numbers are b0=2 and b1=1.
+
+ std::cout << "BETTI NUMBERS" << std::endl;
+
+ BOOST_CHECK(pcoh.betti_number(0) == 2);
+ BOOST_CHECK(pcoh.betti_number(1) == 1);
+ BOOST_CHECK(pcoh.betti_number(2) == 0);
+
+ std::vector<int> bns = pcoh.betti_numbers();
+ BOOST_CHECK(bns.size() == 3);
+ BOOST_CHECK(bns[0] == 2);
+ BOOST_CHECK(bns[1] == 1);
+ BOOST_CHECK(bns[2] == 0);
+
+ std::cout << "GET PERSISTENT PAIRS" << std::endl;
+
+ // Custom sort and output persistence
+ cmp_intervals_by_dim_then_length<Mini_simplex_tree> cmp(&st);
+ auto persistent_pairs = pcoh.get_persistent_pairs();
+
+ std::sort(std::begin(persistent_pairs), std::end(persistent_pairs), cmp);
+
+ BOOST_CHECK(persistent_pairs.size() == 3);
+ // persistent_pairs[0] = 2 1 0 inf
+ BOOST_CHECK(st.dimension(get<0>(persistent_pairs[0])) == 1);
+ BOOST_CHECK(st.filtration(get<0>(persistent_pairs[0])) == 0);
+ BOOST_CHECK(get<1>(persistent_pairs[0]) == st.null_simplex());
+
+ // persistent_pairs[1] = 2 0 0 inf
+ BOOST_CHECK(st.dimension(get<0>(persistent_pairs[1])) == 0);
+ BOOST_CHECK(st.filtration(get<0>(persistent_pairs[1])) == 0);
+ BOOST_CHECK(get<1>(persistent_pairs[1]) == st.null_simplex());
+
+ // persistent_pairs[2] = 2 0 0 inf
+ BOOST_CHECK(st.dimension(get<0>(persistent_pairs[2])) == 0);
+ BOOST_CHECK(st.filtration(get<0>(persistent_pairs[2])) == 0);
+ BOOST_CHECK(get<1>(persistent_pairs[2]) == st.null_simplex());
+
+ std::cout << "INTERVALS IN DIMENSION" << std::endl;
+
+ auto intervals_in_dimension_0 = pcoh.intervals_in_dimension(0);
+ std::cout << "intervals_in_dimension_0.size() = " << intervals_in_dimension_0.size() << std::endl;
+ for (std::size_t i = 0; i < intervals_in_dimension_0.size(); i++)
+ std::cout << "intervals_in_dimension_0[" << i << "] = [" << intervals_in_dimension_0[i].first << "," <<
+ intervals_in_dimension_0[i].second << "]" << std::endl;
+ BOOST_CHECK(intervals_in_dimension_0.size() == 2);
+ BOOST_CHECK(intervals_in_dimension_0[0].first == 0);
+ BOOST_CHECK(intervals_in_dimension_0[0].second == std::numeric_limits<Mini_simplex_tree::Filtration_value>::infinity());
+ BOOST_CHECK(intervals_in_dimension_0[1].first == 0);
+ BOOST_CHECK(intervals_in_dimension_0[1].second == std::numeric_limits<Mini_simplex_tree::Filtration_value>::infinity());
+
+
+ auto intervals_in_dimension_1 = pcoh.intervals_in_dimension(1);
+ std::cout << "intervals_in_dimension_1.size() = " << intervals_in_dimension_1.size() << std::endl;
+ for (std::size_t i = 0; i < intervals_in_dimension_1.size(); i++)
+ std::cout << "intervals_in_dimension_1[" << i << "] = [" << intervals_in_dimension_1[i].first << "," <<
+ intervals_in_dimension_1[i].second << "]" << std::endl;
+ BOOST_CHECK(intervals_in_dimension_1.size() == 1);
+ BOOST_CHECK(intervals_in_dimension_1[0].first == 0);
+ BOOST_CHECK(intervals_in_dimension_1[0].second == std::numeric_limits<Mini_simplex_tree::Filtration_value>::infinity());
+
+ 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);
+}
+
+using Simplex_tree = Gudhi::Simplex_tree<>;
+using St_persistence =
+ Gudhi::persistent_cohomology::Persistent_cohomology<Simplex_tree, Gudhi::persistent_cohomology::Field_Zp>;
+
+BOOST_AUTO_TEST_CASE( betti_numbers )
+{
+ Simplex_tree st;
+
+ /* Complex to build. */
+ /* 1 4 */
+ /* o---o */
+ /* /3\ / */
+ /* o---o o */
+ /* 2 0 5 */
+ const short tetra0123[] = {0, 1, 2, 3};
+ const short edge04[] = {0, 4};
+ const short edge14[] = {1, 4};
+ const short vertex5[] = {5};
+ st.insert_simplex_and_subfaces(tetra0123, 4.0);
+ st.insert_simplex_and_subfaces(edge04, 2.0);
+ st.insert_simplex(edge14, 2.0);
+ st.insert_simplex(vertex5, 1.0);
+
+ // Sort the simplices in the order of the filtration
+ st.initialize_filtration();
+
+ // Class for homology computation
+ St_persistence pcoh(st);
+
+ // Initialize the coefficient field Z/3Z for homology
+ pcoh.init_coefficients(3);
+
+ // Compute the persistence diagram of the complex
+ pcoh.compute_persistent_cohomology();
+
+ // Check the Betti numbers are b0=2, b1=1 and b2=0.
+ BOOST_CHECK(pcoh.betti_number(0) == 2);
+ BOOST_CHECK(pcoh.betti_number(1) == 1);
+ BOOST_CHECK(pcoh.betti_number(2) == 0);
+
+ // Check the Betti numbers are b0=2, b1=1 and b2=0.
+ std::vector<int> bns = pcoh.betti_numbers();
+ BOOST_CHECK(bns.size() == 3);
+ BOOST_CHECK(bns[0] == 2);
+ BOOST_CHECK(bns[1] == 1);
+ BOOST_CHECK(bns[2] == 0);
+
+ // Check the persistent Betti numbers in [4., 10.] are b0=2, b1=1 and b2=0.
+ BOOST_CHECK(pcoh.persistent_betti_number(0, 4., 10.) == 2);
+ BOOST_CHECK(pcoh.persistent_betti_number(1, 4., 10.) == 1);
+ BOOST_CHECK(pcoh.persistent_betti_number(2, 4., 10.) == 0);
+
+ // Check the persistent Betti numbers in [2., 100.] are b0=2, b1=0 and b2=0.
+ BOOST_CHECK(pcoh.persistent_betti_number(0, 2., 100.) == 2);
+ BOOST_CHECK(pcoh.persistent_betti_number(1, 2., 100.) == 0);
+ BOOST_CHECK(pcoh.persistent_betti_number(2, 2., 100.) == 0);
+
+ // Check the persistent Betti numbers in [1., 1000.] are b0=1, b1=0 and b2=0.
+ BOOST_CHECK(pcoh.persistent_betti_number(0, 1., 1000.) == 1);
+ BOOST_CHECK(pcoh.persistent_betti_number(1, 1., 1000.) == 0);
+ BOOST_CHECK(pcoh.persistent_betti_number(2, 1., 1000.) == 0);
+
+ // Check the persistent Betti numbers in [.9, 1000.] are b0=0, b1=0 and b2=0.
+ BOOST_CHECK(pcoh.persistent_betti_number(0, .9, 1000.) == 0);
+ BOOST_CHECK(pcoh.persistent_betti_number(1, .9, 1000.) == 0);
+ BOOST_CHECK(pcoh.persistent_betti_number(2, .9, 1000.) == 0);
+
+ // Check the persistent Betti numbers in [4.1, 10000.] are b0=2, b1=1 and b2=0.
+ bns = pcoh.persistent_betti_numbers(4.1, 10000.);
+ BOOST_CHECK(bns[0] == 2);
+ BOOST_CHECK(bns[1] == 1);
+ BOOST_CHECK(bns[2] == 0);
+
+ // Check the persistent Betti numbers in [2.1, 100000.] are b0=2, b1=0 and b2=0.
+ bns = pcoh.persistent_betti_numbers(2.1, 100000.);
+ BOOST_CHECK(bns[0] == 2);
+ BOOST_CHECK(bns[1] == 0);
+ BOOST_CHECK(bns[2] == 0);
+
+ // Check the persistent Betti numbers in [1.1, 1000000.] are b0=1, b1=0 and b2=0.
+ bns = pcoh.persistent_betti_numbers(1.1, 1000000.);
+ BOOST_CHECK(bns[0] == 1);
+ BOOST_CHECK(bns[1] == 0);
+ BOOST_CHECK(bns[2] == 0);
+
+ // Check the persistent Betti numbers in [.1, 10000000.] are b0=0, b1=0 and b2=0.
+ bns = pcoh.persistent_betti_numbers(.1, 10000000.);
+ BOOST_CHECK(bns[0] == 0);
+ BOOST_CHECK(bns[1] == 0);
+ BOOST_CHECK(bns[2] == 0);
+
+ // Custom sort and output persistence
+ cmp_intervals_by_dim_then_length<Simplex_tree> cmp(&st);
+ auto persistent_pairs = pcoh.get_persistent_pairs();
+
+ std::sort(std::begin(persistent_pairs), std::end(persistent_pairs), cmp);
+
+ BOOST_CHECK(persistent_pairs.size() == 3);
+ // persistent_pairs[0] = 2 1 4 inf
+ BOOST_CHECK(st.dimension(get<0>(persistent_pairs[0])) == 1);
+ BOOST_CHECK(st.filtration(get<0>(persistent_pairs[0])) == 4);
+ BOOST_CHECK(get<1>(persistent_pairs[0]) == st.null_simplex());
+
+ // persistent_pairs[1] = 2 0 2 inf
+ BOOST_CHECK(st.dimension(get<0>(persistent_pairs[1])) == 0);
+ BOOST_CHECK(st.filtration(get<0>(persistent_pairs[1])) == 2);
+ BOOST_CHECK(get<1>(persistent_pairs[1]) == st.null_simplex());
+
+ // persistent_pairs[2] = 2 0 1 inf
+ BOOST_CHECK(st.dimension(get<0>(persistent_pairs[2])) == 0);
+ BOOST_CHECK(st.filtration(get<0>(persistent_pairs[2])) == 1);
+ BOOST_CHECK(get<1>(persistent_pairs[2]) == st.null_simplex());
+
+ std::cout << "INTERVALS IN DIMENSION" << std::endl;
+
+ auto intervals_in_dimension_0 = pcoh.intervals_in_dimension(0);
+ std::cout << "intervals_in_dimension_0.size() = " << intervals_in_dimension_0.size() << std::endl;
+ for (std::size_t i = 0; i < intervals_in_dimension_0.size(); i++)
+ std::cout << "intervals_in_dimension_0[" << i << "] = [" << intervals_in_dimension_0[i].first << "," <<
+ intervals_in_dimension_0[i].second << "]" << std::endl;
+ BOOST_CHECK(intervals_in_dimension_0.size() == 2);
+ BOOST_CHECK(intervals_in_dimension_0[0].first == 2);
+ BOOST_CHECK(intervals_in_dimension_0[0].second == std::numeric_limits<Mini_simplex_tree::Filtration_value>::infinity());
+ BOOST_CHECK(intervals_in_dimension_0[1].first == 1);
+ BOOST_CHECK(intervals_in_dimension_0[1].second == std::numeric_limits<Mini_simplex_tree::Filtration_value>::infinity());
+
+ auto intervals_in_dimension_1 = pcoh.intervals_in_dimension(1);
+ std::cout << "intervals_in_dimension_1.size() = " << intervals_in_dimension_1.size() << std::endl;
+ for (std::size_t i = 0; i < intervals_in_dimension_1.size(); i++)
+ std::cout << "intervals_in_dimension_1[" << i << "] = [" << intervals_in_dimension_1[i].first << "," <<
+ intervals_in_dimension_1[i].second << "]" << std::endl;
+ BOOST_CHECK(intervals_in_dimension_1.size() == 1);
+ BOOST_CHECK(intervals_in_dimension_1[0].first == 4);
+ BOOST_CHECK(intervals_in_dimension_1[0].second == std::numeric_limits<Mini_simplex_tree::Filtration_value>::infinity());
+
+ 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);
+}