1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 1997-9, 2000, 2009-2011 Free Software Foundation, Inc.
4 This program is free software: you can redistribute it and/or modify
5 it under the terms of the GNU General Public License as published by
6 the Free Software Foundation, either version 3 of the License, or
7 (at your option) any later version.
9 This program is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 GNU General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program. If not, see <http://www.gnu.org/licenses/>. */
19 #include <gsl/gsl_rng.h>
24 #include "data/dataset.h"
25 #include "data/variable.h"
26 #include "language/command.h"
27 #include "language/lexer/lexer.h"
28 #include "libpspp/compiler.h"
29 #include "libpspp/message.h"
30 #include "libpspp/str.h"
31 #include "math/random.h"
33 #include "gl/xalloc.h"
36 #define _(msgid) gettext (msgid)
38 /* The two different types of samples. */
41 TYPE_A_FROM_B, /* 5 FROM 10 */
42 TYPE_FRACTION /* 0.5 */
45 /* SAMPLE transformation. */
48 int type; /* One of TYPE_*. */
49 int n, N; /* TYPE_A_FROM_B: n from N. */
50 int m, t; /* TYPE_A_FROM_B: # picked so far; # so far. */
51 unsigned frac; /* TYPE_FRACTION: a fraction of UINT_MAX. */
54 static const struct trns_class sample_trns_class;
57 cmd_sample (struct lexer *lexer, struct dataset *ds)
59 struct sample_trns *trns;
65 if (!lex_force_num (lexer))
67 if (!lex_is_integer (lexer))
69 unsigned long min = gsl_rng_min (get_rng ());
70 unsigned long max = gsl_rng_max (get_rng ());
73 if (!lex_force_num_range_open (lexer, "SAMPLE", 0, 1))
76 frac = lex_tokval (lexer) * (max - min) + min;
82 a = lex_integer (lexer);
84 if (!lex_force_match_id (lexer, "FROM"))
86 if (!lex_force_int_range (lexer, "FROM", a + 1, INT_MAX))
88 b = lex_integer (lexer);
93 trns = xmalloc (sizeof *trns);
97 trns->m = trns->t = 0;
99 add_transformation (ds, &sample_trns_class, trns);
104 /* Executes a SAMPLE transformation. */
105 static enum trns_result
106 sample_trns_proc (void *t_, struct ccase **c UNUSED,
107 casenumber case_num UNUSED)
109 struct sample_trns *t = t_;
112 if (t->type == TYPE_FRACTION)
114 if (gsl_rng_get (get_rng ()) <= t->frac)
115 return TRNS_CONTINUE;
117 return TRNS_DROP_CASE;
121 return TRNS_DROP_CASE;
123 U = gsl_rng_uniform (get_rng ());
124 if ((t->N - t->t) * U >= t->n - t->m)
127 return TRNS_DROP_CASE;
133 return TRNS_CONTINUE;
138 sample_trns_free (void *t_)
140 struct sample_trns *t = t_;
145 static const struct trns_class sample_trns_class = {
147 .execute = sample_trns_proc,
148 .destroy = sample_trns_free,