Mercurial > octave-nkf
view src/DLD-FUNCTIONS/spfind.cc @ 7017:a1dbe9d80eee
[project @ 2007-10-12 21:27:11 by jwe]
author | jwe |
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date | Fri, 12 Oct 2007 21:27:37 +0000 |
parents | 93c65f2a5668 |
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/* Copyright (C) 2006, 2007 David Bateman This file is part of Octave. Octave is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 3 of the License, or (at your option) any later version. Octave 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 General Public License for more details. You should have received a copy of the GNU General Public License along with Octave; see the file COPYING. If not, see <http://www.gnu.org/licenses/>. */ #ifdef HAVE_CONFIG_H #include <config.h> #endif #include <cstdlib> #include <string> #include "variables.h" #include "utils.h" #include "pager.h" #include "defun-dld.h" #include "gripes.h" #include "quit.h" #include "ov-re-sparse.h" #include "ov-cx-sparse.h" template <typename T, typename M> octave_value_list sparse_find_non_zero_elem_idx (const T& v, M& val, int nargout, octave_idx_type n_to_find, int direction) { octave_value_list retval ((nargout == 0 ? 1 : nargout), Matrix ()); octave_idx_type nc = v.cols(); octave_idx_type nr = v.rows(); octave_idx_type nz = v.nnz(); // Search in the default range. octave_idx_type start_nc = -1; octave_idx_type end_nc = -1; octave_idx_type count; // Search for the range to search if (n_to_find < 0) { start_nc = 0; end_nc = nc; n_to_find = nz; count = nz; } else if (direction > 0) { for (octave_idx_type j = 0; j < nc; j++) { OCTAVE_QUIT; if (v.cidx(j) == 0 && v.cidx(j+1) != 0) start_nc = j; if (v.cidx(j+1) >= n_to_find) { end_nc = j + 1; break; } } } else { for (octave_idx_type j = nc; j > 0; j--) { OCTAVE_QUIT; if (v.cidx(j) == nz && v.cidx(j-1) != nz) end_nc = j; if (nz - v.cidx(j-1) >= n_to_find) { start_nc = j - 1; break; } } } count = (n_to_find > v.cidx(end_nc) - v.cidx(start_nc) ? v.cidx(end_nc) - v.cidx(start_nc) : n_to_find); // If the original argument was a row vector, force a row vector of // the overall indices to be returned. But see below for scalar // case... octave_idx_type result_nr = count; octave_idx_type result_nc = 1; bool scalar_arg = false; if (v.rows () == 1) { result_nr = 1; result_nc = count; scalar_arg = (v.columns () == 1); } Matrix idx (result_nr, result_nc); Matrix i_idx (result_nr, result_nc); Matrix j_idx (result_nr, result_nc); val = M(result_nr, result_nc); if (count > 0) { // Search for elements to return. Only search the region where // there are elements to be found using the count that we want // to find. for (octave_idx_type j = start_nc, cx = 0; j < end_nc; j++) for (octave_idx_type i = v.cidx(j); i < v.cidx(j+1); i++ ) { OCTAVE_QUIT; if (direction < 0 && i < nz - count) continue; i_idx (cx) = static_cast<double> (v.ridx(i) + 1); j_idx (cx) = static_cast<double> (j + 1); idx (cx) = j * nr + v.ridx(i) + 1; val (cx) = v.data(i); cx++; if (cx == count) break; } } else if (scalar_arg) { idx.resize (0, 0); i_idx.resize (0, 0); j_idx.resize (0, 0); val.resize (0, 0); } switch (nargout) { case 0: case 1: retval(0) = idx; break; case 5: retval(4) = nc; // Fall through case 4: retval(3) = nr; // Fall through case 3: retval(2) = val; // Fall through! case 2: retval(1) = j_idx; retval(0) = i_idx; break; default: panic_impossible (); break; } return retval; } template octave_value_list sparse_find_non_zero_elem_idx (const SparseMatrix&, Matrix&, int, octave_idx_type, int); template octave_value_list sparse_find_non_zero_elem_idx (const SparseComplexMatrix&, ComplexMatrix&, int, octave_idx_type, int); // PKG_ADD: dispatch ("find", "spfind", "sparse matrix"); // PKG_ADD: dispatch ("find", "spfind", "sparse complex matrix"); // PKG_ADD: dispatch ("find", "spfind", "sparse bool matrix"); DEFUN_DLD (spfind, args, nargout, "-*- texinfo -*-\n\ @deftypefn {Loadable Function} {} spfind (@var{x})\n\ @deftypefnx {Loadable Function} {} spfind (@var{x}, @var{n})\n\ @deftypefnx {Loadable Function} {} spfind (@var{x}, @var{n}, @var{direction})\n\ @deftypefnx {Loadable Function} {[@var{i}, @var{j}, @var{v}} spfind (@dots{})\n\ \n\ A sparse version of the @code{find} function. Please see the @code{find}\n\ for details of its use.\n\ \n\ Note that this function is particularly useful for sparse matrices, as\n\ it extracts the non-zero elements as vectors, which can then be used to\n\ create the original matrix. For example,\n\ \n\ @example\n\ @group\n\ sz = size(a);\n\ [i, j, v] = spfind (a);\n\ b = sparse(i, j, v, sz(1), sz(2));\n\ @end group\n\ @end example\n\ @seealso{sparse}\n\ @end deftypefn") { octave_value_list retval; int nargin = args.length (); if (nargin > 3 || nargin < 1) { print_usage (); return retval; } // Setup the default options. octave_idx_type n_to_find = -1; if (nargin > 1) { n_to_find = args(1).int_value (); if (error_state) { error ("find: expecting second argument to be an integer"); return retval; } } // Direction to do the searching (1 == forward, -1 == reverse). int direction = 1; if (nargin > 2) { direction = 0; std::string s_arg = args(2).string_value (); if (! error_state) { if (s_arg == "first") direction = 1; else if (s_arg == "last") direction = -1; } if (direction == 0) { error ("find: expecting third argument to be \"first\" or \"last\""); return retval; } } octave_value arg = args(0); if (arg.is_real_type ()) { SparseMatrix v = arg.sparse_matrix_value (); Matrix val; if (! error_state) retval = sparse_find_non_zero_elem_idx (v, val, nargout, n_to_find, direction); } else if (arg.is_complex_type ()) { SparseComplexMatrix v = arg.sparse_complex_matrix_value (); ComplexMatrix val; if (! error_state) retval = sparse_find_non_zero_elem_idx (v, val, nargout, n_to_find, direction); } else gripe_wrong_type_arg ("spfind", arg); return retval; } /* ;;; Local Variables: *** ;;; mode: C++ *** ;;; End: *** */