1 /* PSPP - a program for statistical analysis.
2 Copyright (C) 2008, 2009, 2011 Free Software Foundation, Inc.
3
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.
8
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.
13
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/>. */
16
17 #include <config.h>
18
19 #include "math/percentiles.h"
20
21 #include "data/casereader.h"
22 #include "data/val-type.h"
23 #include "data/variable.h"
24 #include "libpspp/assertion.h"
25 #include "libpspp/cast.h"
26 #include "math/order-stats.h"
27
28 #include "gl/xalloc.h"
29
30 #include "gettext.h"
31 #define _(msgid) gettext (msgid)
32 #define N_(msgid) msgid
33
34 const char *const ptile_alg_desc[] = {
35 "",
36 N_("HAverage"),
37 N_("Weighted Average"),
38 N_("Rounded"),
39 N_("Empirical"),
40 N_("Empirical with averaging")
41 };
42
43
44
45 double
percentile_calculate(const struct percentile * ptl,enum pc_alg alg)46 percentile_calculate (const struct percentile *ptl, enum pc_alg alg)
47 {
48 struct percentile *mutable = CONST_CAST (struct percentile *, ptl);
49 const struct order_stats *os = &ptl->parent;
50
51 if (ptl->g1 == SYSMIS)
52 mutable->g1 = (os->k[0].tc - os->k[0].cc) / os->k[0].c_p1;
53
54 if (ptl->g1_star == SYSMIS)
55 mutable->g1_star = os->k[0].tc - os->k[0].cc;
56
57 if (ptl->g2 == SYSMIS)
58 {
59 if (os->k[1].c == 0)
60 mutable->g2 = os->k[1].tc / os->k[1].c_p1;
61 else if (os->k[1].c_p1 == 0)
62 mutable->g2 = 0;
63 else
64 mutable->g2 = (os->k[1].tc - os->k[1].cc) / os->k[1].c_p1;
65 }
66
67 if (ptl->g2_star == SYSMIS)
68 {
69 if (os->k[1].c == 0)
70 mutable->g2_star = os->k[1].tc;
71 else if (os->k[1].c_p1 == 0)
72 mutable->g2_star = 0;
73 else
74 mutable->g2_star = os->k[1].tc - os->k[1].cc;
75 }
76
77 switch (alg)
78 {
79 case PC_WAVERAGE:
80 if (ptl->g1_star >= 1.0)
81 return os->k[0].y_p1;
82 else
83 {
84 double a = (os->k[0].y == SYSMIS) ? 0 : os->k[0].y;
85
86 if (os->k[0].c_p1 >= 1.0)
87 return (1 - ptl->g1_star) * a + ptl->g1_star * os->k[0].y_p1;
88 else
89 return (1 - ptl->g1) * a + ptl->g1 * os->k[0].y_p1;
90 }
91 break;
92
93 case PC_ROUND:
94 {
95 double a = (os->k[0].y == SYSMIS) ? 0 : os->k[0].y;
96
97 if (os->k[0].c_p1 >= 1.0)
98 return (ptl->g1_star < 0.5) ? a : os->k[0].y_p1;
99 else
100 return (ptl->g1 < 0.5) ? a : os->k[0].y_p1;
101 }
102 break;
103
104 case PC_EMPIRICAL:
105 if (ptl->g1_star == 0)
106 return os->k[0].y;
107 else
108 return os->k[0].y_p1;
109 break;
110
111 case PC_HAVERAGE:
112 if (ptl->g2_star >= 1.0)
113 {
114 return os->k[1].y_p1;
115 }
116 else
117 {
118 double a = (os->k[1].y == SYSMIS) ? 0 : os->k[1].y;
119
120 if (os->k[1].c_p1 >= 1.0)
121 {
122 if (ptl->g2_star == 0)
123 return os->k[1].y;
124
125 return (1 - ptl->g2_star) * a + ptl->g2_star * os->k[1].y_p1;
126 }
127 else
128 {
129 return (1 - ptl->g2) * a + ptl->g2 * os->k[1].y_p1;
130 }
131 }
132
133 break;
134
135 case PC_AEMPIRICAL:
136 if (ptl->g1_star == 0)
137 return (os->k[0].y + os->k[0].y_p1)/ 2.0;
138 else
139 return os->k[0].y_p1;
140 break;
141
142 default:
143 NOT_REACHED ();
144 break;
145 }
146
147 NOT_REACHED ();
148
149 return SYSMIS;
150 }
151
152
153 static void
destroy(struct statistic * stat)154 destroy (struct statistic *stat)
155 {
156 struct percentile *ptl = UP_CAST (stat, struct percentile, parent.parent);
157 struct order_stats *os = &ptl->parent;
158 free (os->k);
159 free (ptl);
160 }
161
162
163 struct percentile *
percentile_create(double p,double W)164 percentile_create (double p, double W)
165 {
166 struct percentile *ptl = xzalloc (sizeof (*ptl));
167 struct order_stats *os = &ptl->parent;
168 struct statistic *stat = &os->parent;
169
170 assert (p >= 0);
171 assert (p <= 1.0);
172
173 ptl->ptile = p;
174 ptl->w = W;
175
176 os->n_k = 2;
177 os->k = xcalloc (2, sizeof (*os->k));
178 os->k[0].tc = W * p;
179 os->k[1].tc = (W + 1.0) * p;
180
181 ptl->g1 = ptl->g1_star = SYSMIS;
182 ptl->g2 = ptl->g2_star = SYSMIS;
183
184 os->k[1].y_p1 = os->k[1].y = SYSMIS;
185 os->k[0].y_p1 = os->k[0].y = SYSMIS;
186
187 stat->destroy = destroy;
188
189 return ptl;
190 }
191
192