1 /* lib/linreg/coefficient.c
3 Copyright (C) 2005 Free Software Foundation, Inc.
4 Written by Jason H Stover.
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 2 of the License, or (at
9 your option) any later version.
11 This program is distributed in the hope that it will be useful, but
12 WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
14 General Public License for more details.
16 You should have received a copy of the GNU General Public License
17 along with this program; if not, write to the Free Software
18 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
23 Accessor functions for matching coefficients and variables.
26 #include <math/linreg/coefficient.h>
27 #include <math/linreg/linreg.h>
28 #include "src/math/design-matrix.h"
29 #include "src/data/variable.h"
30 #include "src/data/value.h"
32 #include <gl/xalloc.h>
37 const struct variable *v; /* Variable associated with this
38 coefficient. Note this variable may not
39 be unique. In other words, a
40 coefficient structure may have other
41 v_info's, each with its own variable.
43 const union value *val; /* Value of the variable v which this
44 varinfo refers to. This member is relevant
45 only to categorical variables.
49 void pspp_linreg_coeff_free (struct pspp_linreg_coeff *c)
55 Initialize the variable and value pointers inside the
56 coefficient structures for the linear model.
59 pspp_linreg_coeff_init (pspp_linreg_cache *c, struct design_matrix *X)
64 struct pspp_linreg_coeff *coeff;
67 xnmalloc (X->m->size2 + 1,
69 for (i = 0; i < X->m->size2; i++)
71 j = i + 1; /* The first coefficient is the intercept. */
73 coeff->n_vars = n_vals; /* Currently, no procedures allow interactions.
74 This will have to change when procedures that
75 allow interaction terms are written.
77 coeff->v_info = xnmalloc (coeff->n_vars, sizeof (*coeff->v_info));
78 assert (coeff->v_info != NULL);
79 coeff->v_info->v = (const struct variable *) design_matrix_col_to_var (X, i);
81 if (coeff->v_info->v->type == ALPHA)
84 k = design_matrix_var_to_column (X, coeff->v_info->v);
87 coeff->v_info->val = cat_subscript_to_value (k, (struct variable *) coeff->v_info->v);
92 pspp_linreg_coeff_set_estimate (struct pspp_linreg_coeff *c,
95 c->estimate = estimate;
98 pspp_linreg_coeff_set_std_err (struct pspp_linreg_coeff *c,
101 c->std_err = std_err;
104 How many variables are associated with this coefficient?
107 pspp_linreg_coeff_get_n_vars (struct pspp_linreg_coeff *c)
112 Which variable does this coefficient match?
114 const struct variable *
115 pspp_linreg_coeff_get_var (struct pspp_linreg_coeff *c, int i)
117 assert (i < c->n_vars);
118 return (c->v_info + i)->v;
121 Which value is associated with this coefficient/variable comination?
124 pspp_linreg_coeff_get_value (struct pspp_linreg_coeff *c,
125 const struct variable *v)
128 const struct variable *candidate;
130 while (i < c->n_vars)
132 candidate = pspp_linreg_coeff_get_var (c, i);
133 if (v->index == candidate->index)
135 return (c->v_info + i)->val;