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Diffstat (limited to 'src/simple_example.cpp')
-rw-r--r-- | src/simple_example.cpp | 127 |
1 files changed, 127 insertions, 0 deletions
diff --git a/src/simple_example.cpp b/src/simple_example.cpp new file mode 100644 index 0000000..aff3ff9 --- /dev/null +++ b/src/simple_example.cpp @@ -0,0 +1,127 @@ +/* Copyright 2013 IST Austria + Contributed by: Ulrich Bauer, Michael Kerber, Jan Reininghaus + + This file is part of PHAT. + + PHAT is free software: you can redistribute it and/or modify + it under the terms of the GNU Lesser General Public License as published by + the Free Software Foundation, either version 3 of the License, or + (at your option) any later version. + + PHAT is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + GNU Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public License + along with PHAT. If not, see <http://www.gnu.org/licenses/>. */ + +// This file contains a simple example that demonstrates the usage of the library interface + +// wrapper algorithm that computes the persistence pairs of a given boundary matrix using a specified algorithm +#include <phat/compute_persistence_pairs.h> + +// main data structure (choice affects performance) +#include <phat/representations/vector_vector.h> + +// algorithm (choice affects performance) +#include <phat/algorithms/standard_reduction.h> +#include <phat/algorithms/chunk_reduction.h> +#include <phat/algorithms/row_reduction.h> +#include <phat/algorithms/twist_reduction.h> + +int main( int argc, char** argv ) +{ + std::cout << "We will build an ordered boundary matrix of this simplicial complex consisting of a single triangle: " << std::endl; + std::cout << std::endl; + std::cout << " 3" << std::endl; + std::cout << " |\\" << std::endl; + std::cout << " | \\" << std::endl; + std::cout << " | \\" << std::endl; + std::cout << " | \\ 4" << std::endl; + std::cout << "5| \\" << std::endl; + std::cout << " | \\" << std::endl; + std::cout << " | 6 \\" << std::endl; + std::cout << " | \\" << std::endl; + std::cout << " |________\\" << std::endl; + std::cout << " 0 2 1" << std::endl; + + + // first define a boundary matrix with the chosen internal representation + phat::boundary_matrix< phat::vector_vector > boundary_matrix; + + // set the number of columns (has to be 7 since we have 7 simplices) + boundary_matrix.set_num_cols( 7 ); + + // set the dimension of the cell that a column represents: + boundary_matrix.set_dim( 0, 0 ); + boundary_matrix.set_dim( 1, 0 ); + boundary_matrix.set_dim( 2, 1 ); + boundary_matrix.set_dim( 3, 0 ); + boundary_matrix.set_dim( 4, 1 ); + boundary_matrix.set_dim( 5, 1 ); + boundary_matrix.set_dim( 6, 2 ); + + // set the respective columns -- the columns entries have to be sorted + std::vector< phat::index > temp_col; + + boundary_matrix.set_col( 0, temp_col ); + + boundary_matrix.set_col( 1, temp_col ); + + temp_col.push_back( 0 ); + temp_col.push_back( 1 ); + boundary_matrix.set_col( 2, temp_col ); + temp_col.clear(); + + boundary_matrix.set_col( 3, temp_col ); + + temp_col.push_back( 1 ); + temp_col.push_back( 3 ); + boundary_matrix.set_col( 4, temp_col ); + temp_col.clear(); + + temp_col.push_back( 0 ); + temp_col.push_back( 3 ); + boundary_matrix.set_col( 5, temp_col ); + temp_col.clear(); + + temp_col.push_back( 2 ); + temp_col.push_back( 4 ); + temp_col.push_back( 5 ); + boundary_matrix.set_col( 6, temp_col ); + temp_col.clear(); + + // print some information of the boundary matrix: + std::cout << std::endl; + std::cout << "The boundary matrix has " << boundary_matrix.get_num_cols() << " columns: " << std::endl; + for( phat::index col_idx = 0; col_idx < boundary_matrix.get_num_cols(); col_idx++ ) { + std::cout << "Colum " << col_idx << " represents a cell of dimension " << (int)boundary_matrix.get_dim( col_idx ) << ". "; + if( !boundary_matrix.is_empty( col_idx ) ) { + std::vector< phat::index > temp_col; + boundary_matrix.get_col( col_idx, temp_col ); + std::cout << "Its boundary consists of the cells"; + for( phat::index idx = 0; idx < (phat::index)temp_col.size(); idx++ ) + std::cout << " " << temp_col[ idx ]; + } + std::cout << std::endl; + } + std::cout << "Overall, the boundary matrix has " << boundary_matrix.get_num_entries() << " entries." << std::endl; + + + // define the object to hold the resulting persistence pairs + phat::persistence_pairs pairs; + + // choose an algorithm (choice affects performance) and compute the persistence pair + // (modifies boundary_matrix) + phat::compute_persistence_pairs< phat::twist_reduction >( pairs, boundary_matrix ); + + // sort the persistence pairs by birth index + pairs.sort(); + + // print the pairs: + std::cout << std::endl; + std::cout << "There are " << pairs.get_num_pairs() << " persistence pairs: " << std::endl; + for( phat::index idx = 0; idx < pairs.get_num_pairs(); idx++ ) + std::cout << "Birth: " << pairs.get_pair( idx ).first << ", Death: " << pairs.get_pair( idx ).second << std::endl; +} |