+/*
+ lib/linreg/coefficient.c
+
+ Copyright (C) 2005 Free Software Foundation, Inc. Written by Jason H Stover.
+
+ This program 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 2 of the License, or (at your option)
+ any later version.
+
+ This program 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
+ this program; if not, write to the Free Software Foundation, Inc., 51
+ Franklin Street, Fifth Floor, Boston, MA 02111-1307, USA.
+*/
+
+/*
+ Accessor functions for matching coefficients and variables.
+ */
+#include <math/coefficient.h>
+#include <math/linreg/linreg.h>
+#include "src/math/design-matrix.h"
+
+#include <gl/xalloc.h>
+
+
+struct varinfo
+{
+ const struct variable *v; /* Variable associated with this
+ coefficient. Note this variable
+ may not be unique. In other words,
+ a coefficient structure may have
+ other v_info's, each with its own
+ variable. */
+ const union value *val; /* Value of the variable v which this varinfo
+ refers to. This member is relevant only to
+ categorical variables. */
+};
+
+void
+pspp_linreg_coeff_free (struct pspp_linreg_coeff *c)
+{
+ free (c->v_info);
+ free (c);
+}
+
+/*
+ Initialize the variable and value pointers inside the
+ coefficient structures for the linear model.
+ */
+void
+pspp_linreg_coeff_init (pspp_linreg_cache * c, struct design_matrix *X)
+{
+ size_t i;
+ size_t j;
+ int n_vals = 1;
+ struct pspp_linreg_coeff *coeff;
+
+ c->coeff = xnmalloc (X->m->size2 + 1, sizeof (*c->coeff));
+ c->coeff[0] = xmalloc (sizeof (*c->coeff[0]));
+ c->coeff[0]->v_info = NULL; /* Intercept has no associated variable. */
+ for (i = 0; i < X->m->size2; i++)
+ {
+ j = i + 1; /* The first coefficient is the intercept. */
+ c->coeff[j] = xmalloc (sizeof (*c->coeff[j]));
+ coeff = c->coeff[j];
+ coeff->n_vars = n_vals; /* Currently, no procedures allow
+ interactions. This line will have to
+ change when procedures that allow
+ interaction terms are written.
+ */
+ coeff->v_info = xnmalloc (coeff->n_vars, sizeof (*coeff->v_info));
+ assert (coeff->v_info != NULL);
+ coeff->v_info->v =
+ (const struct variable *) design_matrix_col_to_var (X, i);
+
+ if (coeff->v_info->v->type == ALPHA)
+ {
+ size_t k;
+ k = design_matrix_var_to_column (X, coeff->v_info->v);
+ assert (k <= i);
+ k = i - k;
+ coeff->v_info->val =
+ cat_subscript_to_value (k, (struct variable *) coeff->v_info->v);
+ }
+ }
+}
+void
+pspp_linreg_coeff_set_estimate (struct pspp_linreg_coeff *c, double estimate)
+{
+ c->estimate = estimate;
+}
+
+void
+pspp_linreg_coeff_set_std_err (struct pspp_linreg_coeff *c, double std_err)
+{
+ c->std_err = std_err;
+}
+
+/*
+ Return the estimated value of the coefficient.
+ */
+double
+pspp_linreg_coeff_get_est (const struct pspp_linreg_coeff *c)
+{
+ if (c == NULL)
+ {
+ return 0.0;
+ }
+ return c->estimate;
+}
+
+/*
+ Return the standard error of the estimated coefficient.
+*/
+double
+pspp_linreg_coeff_get_std_err (const struct pspp_linreg_coeff *c)
+{
+ if (c == NULL)
+ {
+ return 0.0;
+ }
+ return c->std_err;
+}
+
+/*
+ How many variables are associated with this coefficient?
+ */
+int
+pspp_linreg_coeff_get_n_vars (struct pspp_linreg_coeff *c)
+{
+ if (c == NULL)
+ {
+ return 0;
+ }
+ return c->n_vars;
+}
+
+/*
+ Which variable does this coefficient match? I should be
+ 0 unless the coefficient refers to an interaction term.
+ */
+const struct variable *
+pspp_linreg_coeff_get_var (struct pspp_linreg_coeff *c, int i)
+{
+ if (c == NULL)
+ {
+ return NULL;
+ }
+ assert (i < c->n_vars);
+ return (c->v_info + i)->v;
+}
+
+/*
+ Which value is associated with this coefficient/variable combination?
+ */
+const union value *
+pspp_linreg_coeff_get_value (struct pspp_linreg_coeff *c,
+ const struct variable *v)
+{
+ int i = 0;
+ const struct variable *candidate;
+
+ if (c == NULL || v == NULL)
+ {
+ return NULL;
+ }
+ if (v->type == NUMERIC)
+ {
+ return NULL;
+ }
+ while (i < c->n_vars)
+ {
+ candidate = pspp_linreg_coeff_get_var (c, i);
+ if (v->index == candidate->index)
+ {
+ return (c->v_info + i)->val;
+ }
+ i++;
+ }
+ return NULL;
+}
+
+/*
+ Which coefficient is associated with V? The VAL argument is relevant
+ only to categorical variables.
+ */
+const struct pspp_linreg_coeff *
+pspp_linreg_get_coeff (const pspp_linreg_cache * c,
+ const struct variable *v, const union value *val)
+{
+ int i = 1;
+ struct pspp_linreg_coeff *result = NULL;
+ const struct variable *tmp = NULL;
+
+ if (c == NULL)
+ {
+ return NULL;
+ }
+ if (c->coeff == NULL || c->n_indeps == 0 || v == NULL)
+ {
+ return NULL;
+ }
+
+ result = c->coeff[i];
+ tmp = pspp_linreg_coeff_get_var (result, 0);
+ while (tmp->index != v->index && i < c->n_coeffs)
+ {
+ result = c->coeff[i];
+ tmp = pspp_linreg_coeff_get_var (result, 0);
+ i++;
+ }
+ if (i > c->n_coeffs)
+ {
+ return NULL;
+ }
+ if (v->type == NUMERIC)
+ {
+ return result;
+ }
+ else if (val != NULL)
+ {
+ /*
+ If v is categorical, we need to ensure the coefficient
+ matches the VAL.
+ */
+ while (tmp->index != v->index && i < c->n_coeffs
+ && compare_values (pspp_linreg_coeff_get_value (result, tmp),
+ val, v->width))
+ { /* FIX THIS */
+ i++;
+ result = c->coeff[i];
+ tmp = pspp_linreg_coeff_get_var (result, 0);
+ }
+ if (i == c->n_coeffs)
+ {
+ return NULL;
+ }
+ return result;
+ }
+ return NULL;
+}