Mercurial > hg > octave-lyh
changeset 6002:c5d0490aad55
[project @ 2006-09-26 19:45:42 by jwe]
author | jwe |
---|---|
date | Tue, 26 Sep 2006 19:45:43 +0000 |
parents | d45cb743ff2e |
children | 7f8e4f5e2eb7 |
files | src/ChangeLog src/DLD-FUNCTIONS/find.cc |
diffstat | 2 files changed, 97 insertions(+), 13 deletions(-) [+] |
line wrap: on
line diff
--- a/src/ChangeLog +++ b/src/ChangeLog @@ -1,3 +1,8 @@ +2006-05-17 Bill Denney <bill@givebillmoney.com> + + * DLD-FUNCTIONS/find.cc (find_nonzero_elem_idx, Ffind): + Handle direction and limit on number of elements to find. + 2006-09-26 John W. Eaton <jwe@octave.org> * error.cc (warning_1): Call error_2, not error.
--- a/src/DLD-FUNCTIONS/find.cc +++ b/src/DLD-FUNCTIONS/find.cc @@ -32,26 +32,56 @@ #include "gripes.h" #include "oct-obj.h" -inline double real (double x) { return x; } +// 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 T& nda, int nargout) +find_nonzero_elem_idx (const T& nda, int nargout, octave_idx_type n_to_find, + int direction) { - octave_value_list retval (((nargout == 0) ? 1 : nargout), Matrix ()); + octave_value_list retval ((nargout == 0 ? 1 : nargout), Matrix ()); octave_idx_type count = 0; octave_idx_type nel = nda.nelem (); - for (octave_idx_type i = 0; i < nel; i++) + // Set the starting element to the correct value based on the + // direction to search. + octave_idx_type k = 0; + if (direction == -1) + k = nel - 1; + + // Search in the default range. + octave_idx_type start_el = -1; + octave_idx_type end_el = -1; + + // Search for the number of elements to return. + while (k < nel && k > -1 && n_to_find != count) { OCTAVE_QUIT; - if (nda(i) != 0.0) - count++; + if (nda(k) != 0.0) + { + end_el = k; + if (start_el == -1) + start_el = k; + count++; + } + k = k + direction; } + // Reverse the range if we're looking backward. + if (direction == -1) + { + octave_idx_type tmp_el = start_el; + start_el = end_el; + end_el = tmp_el; + } + // Fix an off by one error. + end_el++; + // 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... @@ -85,7 +115,10 @@ octave_idx_type i = 0; octave_idx_type j = 0; - for (octave_idx_type k = 0; k < nel; k++) + // 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 (k = start_el; k < end_el; k++) { OCTAVE_QUIT; @@ -145,13 +178,17 @@ return retval; } -template octave_value_list find_nonzero_elem_idx (const NDArray&, int); +template octave_value_list find_nonzero_elem_idx (const NDArray&, int, + octave_idx_type, int); -template octave_value_list find_nonzero_elem_idx (const ComplexNDArray&, int); +template octave_value_list find_nonzero_elem_idx (const ComplexNDArray&, int, + octave_idx_type, int); DEFUN_DLD (find, args, nargout, "-*- texinfo -*-\n\ @deftypefn {Loadable Function} {} find (@var{x})\n\ +@deftypefnx {Loadable Function} {} find (@var{x}, @var{n})\n\ +@deftypefnx {Loadable Function} {} find (@var{x}, @var{n}, @var{direction})\n\ Return a vector of indices of nonzero elements of a matrix. To obtain a\n\ single index for each matrix element, Octave pretends that the columns\n\ of a matrix form one long vector (like Fortran arrays are stored). For\n\ @@ -186,18 +223,60 @@ @result{} v = [ 3; 3 ]\n\ @end group\n\ @end example\n\ +\n\ +If two inputs are given, @var{n} indicates the number of elements to\n\ +find from the beginning of the matrix or vector.\n\ +\n\ +If three inputs are given, @var{direction} should be one of \"first\" or\n\ +\"last\" indicating that it should start counting found elements from the\n\ +first or last element.\n\ @end deftypefn") { octave_value_list retval; int nargin = args.length (); - if (nargin != 1 || nargout > 3) + 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 ()) @@ -205,21 +284,21 @@ NDArray nda = arg.array_value (); if (! error_state) - retval = find_nonzero_elem_idx (nda, nargout); + retval = find_nonzero_elem_idx (nda, nargout, n_to_find, direction); } else if (arg.is_complex_type ()) { ComplexNDArray cnda = arg.complex_array_value (); if (! error_state) - retval = find_nonzero_elem_idx (cnda, nargout); + retval = find_nonzero_elem_idx (cnda, nargout, n_to_find, direction); } else if (arg.is_string ()) { charNDArray cnda = arg.char_array_value (); if (! error_state) - retval = find_nonzero_elem_idx (cnda, nargout); + retval = find_nonzero_elem_idx (cnda, nargout, n_to_find, direction); } else {