Mercurial > octave
view libinterp/corefcn/find.cc @ 32046:39700c1ea93e
maint: merge stable to default
author | Rik <rik@octave.org> |
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date | Thu, 20 Apr 2023 18:59:26 -0700 |
parents | 597f3ee61a48 |
children | 2f3b54f81947 2e484f9f1f18 |
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//////////////////////////////////////////////////////////////////////// // // Copyright (C) 1996-2023 The Octave Project Developers // // See the file COPYRIGHT.md in the top-level directory of this // distribution or <https://octave.org/copyright/>. // // 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 // <https://www.gnu.org/licenses/>. // //////////////////////////////////////////////////////////////////////// #if defined (HAVE_CONFIG_H) # include "config.h" #endif #include "quit.h" #include "defun.h" #include "error.h" #include "errwarn.h" #include "ovl.h" OCTAVE_BEGIN_NAMESPACE(octave) // Find at most N_TO_FIND nonzero elements in NDA. Search forward if // DIRECTION is 1, backward if it is -1. NARGOUT is the number of // output arguments. If N_TO_FIND is -1, find all nonzero elements. template <typename T> octave_value_list find_nonzero_elem_idx (const Array<T>& nda, int nargout, octave_idx_type n_to_find, int direction) { octave_value_list retval ((nargout == 0 ? 1 : nargout), Matrix ()); Array<octave_idx_type> idx; if (n_to_find >= 0) idx = nda.find (n_to_find, direction == -1); else idx = nda.find (); // The maximum element is always at the end. octave_idx_type iext = (idx.isempty () ? 0 : idx.xelem (idx.numel () - 1) + 1); switch (nargout) { default: case 3: retval(2) = Array<T> (nda.index (idx_vector (idx))); OCTAVE_FALLTHROUGH; case 2: { Array<octave_idx_type> jdx (idx.dims ()); octave_idx_type n = idx.numel (); octave_idx_type nr = nda.rows (); for (octave_idx_type i = 0; i < n; i++) { jdx.xelem (i) = idx.xelem (i) / nr; idx.xelem (i) %= nr; } iext = -1; retval(1) = idx_vector (jdx, -1); } OCTAVE_FALLTHROUGH; case 1: case 0: retval(0) = idx_vector (idx, iext); break; } return retval; } template <typename T> octave_value_list find_nonzero_elem_idx (const Sparse<T>& v, int nargout, octave_idx_type n_to_find, int direction) { nargout = std::min (nargout, 5); octave_value_list retval ((nargout == 0 ? 1 : nargout), Matrix ()); octave_idx_type nr = v.rows (); octave_idx_type nc = v.cols (); 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; } 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); octave_idx_type result_nr; octave_idx_type result_nc; // Default case is to return a column vector, however, if the original // argument was a row vector, then force return of a row vector. if (nr == 1) { result_nr = 1; result_nc = count; } else { result_nr = count; result_nc = 1; } Matrix idx (result_nr, result_nc); Matrix i_idx (result_nr, result_nc); Matrix j_idx (result_nr, result_nc); Array<T> val (dim_vector (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 { // No items found. Fixup return dimensions for Matlab compatibility. // The behavior to match is documented in Array.cc (Array<T>::find). if ((nr == 0 && nc == 0) || (nr == 1 && nc == 1)) { idx.resize (0, 0); i_idx.resize (0, 0); j_idx.resize (0, 0); val.resize (dim_vector (0, 0)); } } switch (nargout) { case 0: case 1: retval(0) = idx; break; case 5: retval(4) = nc; OCTAVE_FALLTHROUGH; case 4: retval(3) = nr; OCTAVE_FALLTHROUGH; case 3: retval(2) = val; OCTAVE_FALLTHROUGH; case 2: retval(1) = j_idx; retval(0) = i_idx; } return retval; } octave_value_list find_nonzero_elem_idx (const PermMatrix& v, int nargout, octave_idx_type n_to_find, int direction) { // There are far fewer special cases to handle for a PermMatrix. nargout = std::min (nargout, 5); octave_value_list retval ((nargout == 0 ? 1 : nargout), Matrix ()); octave_idx_type nr = v.rows (); octave_idx_type nc = v.cols (); octave_idx_type start_nc, count; // Determine the range to search. if (n_to_find < 0 || n_to_find >= nc) { start_nc = 0; count = nc; } else if (direction > 0) { start_nc = 0; count = n_to_find; } else { start_nc = nc - n_to_find; count = n_to_find; } Matrix idx (count, 1); Matrix i_idx (count, 1); Matrix j_idx (count, 1); // Every value is 1. Array<double> val (dim_vector (count, 1), 1.0); if (count > 0) { const Array<octave_idx_type>& p = v.col_perm_vec (); for (octave_idx_type k = 0; k < count; k++) { octave_quit (); const octave_idx_type j = start_nc + k; const octave_idx_type i = p(j); i_idx(k) = static_cast<double> (1+i); j_idx(k) = static_cast<double> (1+j); idx(k) = j * nc + i + 1; } } else { // FIXME: Is this case even possible? A scalar permutation matrix seems // to devolve to a scalar full matrix, at least from the Octave command // line. Perhaps this function could be called internally from C++ with // such a matrix. // No items found. Fixup return dimensions for Matlab compatibility. // The behavior to match is documented in Array.cc (Array<T>::find). if ((nr == 0 && nc == 0) || (nr == 1 && nc == 1)) { idx.resize (0, 0); i_idx.resize (0, 0); j_idx.resize (0, 0); val.resize (dim_vector (0, 0)); } } switch (nargout) { case 0: case 1: retval(0) = idx; break; case 5: retval(4) = nc; OCTAVE_FALLTHROUGH; case 4: retval(3) = nc; OCTAVE_FALLTHROUGH; case 3: retval(2) = val; OCTAVE_FALLTHROUGH; case 2: retval(1) = j_idx; retval(0) = i_idx; } return retval; } DEFUN (find, args, nargout, doc: /* -*- texinfo -*- @deftypefn {} {@var{idx} =} find (@var{x}) @deftypefnx {} {@var{idx} =} find (@var{x}, @var{n}) @deftypefnx {} {@var{idx} =} find (@var{x}, @var{n}, @var{direction}) @deftypefnx {} {[i, j] =} find (@dots{}) @deftypefnx {} {[i, j, v] =} find (@dots{}) Return a vector of indices of nonzero elements of a matrix, as a row if @var{x} is a row vector or as a column otherwise. To obtain a single index for each matrix element, Octave pretends that the columns of a matrix form one long vector (like Fortran arrays are stored). For example: @example @group find (eye (2)) @result{} [ 1; 4 ] @end group @end example If two inputs are given, @var{n} indicates the maximum number of elements to find from the beginning of the matrix or vector. If three inputs are given, @var{direction} should be one of @qcode{"first"} or @qcode{"last"}, requesting only the first or last @var{n} indices, respectively. However, the indices are always returned in ascending order. If two outputs are requested, @code{find} returns the row and column indices of nonzero elements of a matrix. For example: @example @group [i, j] = find (2 * eye (2)) @result{} i = [ 1; 2 ] @result{} j = [ 1; 2 ] @end group @end example If three outputs are requested, @code{find} also returns a vector containing the nonzero values. For example: @example @group [i, j, v] = find (3 * eye (2)) @result{} i = [ 1; 2 ] @result{} j = [ 1; 2 ] @result{} v = [ 3; 3 ] @end group @end example If @var{x} is a multi-dimensional array of size m x n x p x @dots{}, @var{j} contains the column locations as if @var{x} was flattened into a two-dimensional matrix of size m x (n + p + @dots{}). Note that this function is particularly useful for sparse matrices, as it extracts the nonzero elements as vectors, which can then be used to create the original matrix. For example: @example @group sz = size (a); [i, j, v] = find (a); b = sparse (i, j, v, sz(1), sz(2)); @end group @end example @seealso{nonzeros} @end deftypefn */) { int nargin = args.length (); if (nargin < 1 || nargin > 3) print_usage (); // Setup the default options. octave_idx_type n_to_find = -1; if (nargin > 1) { double val = args(1).xscalar_value ("find: N must be an integer"); if (val < 0 || (! math::isinf (val) && val != math::fix (val))) error ("find: N must be a non-negative integer"); else if (! math::isinf (val)) n_to_find = val; } // Direction to do the searching (1 == forward, -1 == reverse). int direction = 1; if (nargin > 2) { std::string s_arg = args(2).string_value (); if (s_arg == "first") direction = 1; else if (s_arg == "last") direction = -1; else error (R"(find: DIRECTION must be "first" or "last")"); } octave_value_list retval; octave_value arg = args(0); if (arg.islogical ()) { if (arg.issparse ()) { SparseBoolMatrix v = arg.sparse_bool_matrix_value (); retval = find_nonzero_elem_idx (v, nargout, n_to_find, direction); } else if (nargout <= 1 && n_to_find == -1 && direction == 1) { // This case is equivalent to extracting indices from a logical // matrix. Try to reuse the possibly cached index vector. // No need to catch index_exception, since arg is bool. // Out-of-range errors have already set pos, and will be // caught later. octave_value result = arg.index_vector ().unmask (); dim_vector dv = result.dims (); retval(0) = (dv.all_zero () || dv.isvector () ? result : result.reshape (dv.as_column ())); } else { boolNDArray v = arg.bool_array_value (); retval = find_nonzero_elem_idx (v, nargout, n_to_find, direction); } } else if (arg.isinteger ()) { #define DO_INT_BRANCH(INTT) \ else if (arg.is_ ## INTT ## _type ()) \ { \ INTT ## NDArray v = arg.INTT ## _array_value (); \ \ retval = find_nonzero_elem_idx (v, nargout, n_to_find, direction); \ } if (false) ; DO_INT_BRANCH (int8) DO_INT_BRANCH (int16) DO_INT_BRANCH (int32) DO_INT_BRANCH (int64) DO_INT_BRANCH (uint8) DO_INT_BRANCH (uint16) DO_INT_BRANCH (uint32) DO_INT_BRANCH (uint64) else panic_impossible (); } else if (arg.issparse ()) { if (arg.isreal ()) { SparseMatrix v = arg.sparse_matrix_value (); retval = find_nonzero_elem_idx (v, nargout, n_to_find, direction); } else if (arg.iscomplex ()) { SparseComplexMatrix v = arg.sparse_complex_matrix_value (); retval = find_nonzero_elem_idx (v, nargout, n_to_find, direction); } else err_wrong_type_arg ("find", arg); } else if (arg.is_perm_matrix ()) { PermMatrix P = arg.perm_matrix_value (); retval = find_nonzero_elem_idx (P, nargout, n_to_find, direction); } else if (arg.is_string ()) { charNDArray chnda = arg.char_array_value (); retval = find_nonzero_elem_idx (chnda, nargout, n_to_find, direction); } else if (arg.is_single_type ()) { if (arg.isreal ()) { FloatNDArray nda = arg.float_array_value (); retval = find_nonzero_elem_idx (nda, nargout, n_to_find, direction); } else if (arg.iscomplex ()) { FloatComplexNDArray cnda = arg.float_complex_array_value (); retval = find_nonzero_elem_idx (cnda, nargout, n_to_find, direction); } } else if (arg.isreal ()) { NDArray nda = arg.array_value (); retval = find_nonzero_elem_idx (nda, nargout, n_to_find, direction); } else if (arg.iscomplex ()) { ComplexNDArray cnda = arg.complex_array_value (); retval = find_nonzero_elem_idx (cnda, nargout, n_to_find, direction); } else err_wrong_type_arg ("find", arg); return retval; } /* %!assert (find (char ([0, 97])), 2) %!assert (find ([1, 0, 1, 0, 1]), [1, 3, 5]) %!assert (find ([1; 0; 3; 0; 1]), [1; 3; 5]) %!assert (find ([0, 0, 2; 0, 3, 0; -1, 0, 0]), [3; 5; 7]) %!assert <*53603> (find (ones (1,1,2) > 0), [1;2]) %!assert <*53603> (find (ones (1,1,1,3) > 0), [1;2;3]) %!test %! [i, j, v] = find ([0, 0, 2; 0, 3, 0; -1, 0, 0]); %! %! assert (i, [3; 2; 1]); %! assert (j, [1; 2; 3]); %! assert (v, [-1; 3; 2]); %!assert (find (single ([1, 0, 1, 0, 1])), [1, 3, 5]) %!assert (find (single ([1; 0; 3; 0; 1])), [1; 3; 5]) %!assert (find (single ([0, 0, 2; 0, 3, 0; -1, 0, 0])), [3; 5; 7]) %!test %! [i, j, v] = find (single ([0, 0, 2; 0, 3, 0; -1, 0, 0])); %! %! assert (i, [3; 2; 1]); %! assert (j, [1; 2; 3]); %! assert (v, single ([-1; 3; 2])); %!test %! pcol = [5 1 4 3 2]; %! P = eye (5) (:, pcol); %! [i, j, v] = find (P); %! [ifull, jfull, vfull] = find (full (P)); %! assert (i, ifull); %! assert (j, jfull); %! assert (all (v == 1)); %!test %! prow = [5 1 4 3 2]; %! P = eye (5) (prow, :); %! [i, j, v] = find (P); %! [ifull, jfull, vfull] = find (full (P)); %! assert (i, ifull); %! assert (j, jfull); %! assert (all (v == 1)); %!test <*61986> %! P = cat (3, eye(3), eye(3)); %! loc = find (P); %! [i, j, v] = find(P); %! assert (loc, [1, 5, 9, 10, 14, 18]'); %! assert (i, [1, 2, 3, 1, 2, 3]'); %! assert (j, [1, 2, 3, 4, 5, 6]'); %! assert (v, [1, 1, 1, 1, 1, 1]'); %!assert <*53655> (find (false), zeros (0, 0)) %!assert <*53655> (find ([false, false]), zeros (1, 0)) %!assert <*53655> (find ([false; false]), zeros (0, 1)) %!assert <*53655> (find ([false, false; false, false]), zeros (0, 1)) %!assert (find ([2 0 1 0 5 0], 1), 1) %!assert (find ([2 0 1 0 5 0], 2, "last"), [3, 5]) %!assert (find ([2 0 1 0 5 0], Inf), [1, 3, 5]) %!assert (find ([2 0 1 0 5 0], Inf, "last"), [1, 3, 5]) %!error find () */ OCTAVE_END_NAMESPACE(octave)