added function to retrieve variable list used in linear model

diff --git a/src/math/linreg/ChangeLog b/src/math/linreg/ChangeLog
index 274faf41947910f36327ea6880c5280888a151f8..6b4425c07779416edc3916a077da3202f022ec63 100644 (file)
--- a/src/math/linreg/ChangeLog
+++ b/src/math/linreg/ChangeLog
@@ -1,3 +1,14 @@
+2006-04-28  Jason Stover  <jhs@math.gcsu.edu>
+
+       * linreg.c (pspp_linreg_get_vars): New function. Fills an array with
+       pointers to the variables used in the model.
+
+       * linreg.h: Add a pointer called get_vars to pspp_linreg_get_vars()
+       to access variables in a model.
+
+       * coefficient.c (pspp_linreg_coeff_init): Set the variable
+       associated with the intercept term to NULL.
+
 2006-04-26  Jason Stover  <jhs@math.gcsu.edu>
 
        * linreg.h: Added a pointer to predicted values.

diff --git a/src/math/linreg/coefficient.c b/src/math/linreg/coefficient.c
index d1fcbfa2e4bb6a145d0404c9d5493c7c397a62a8..1f5d9ec4031e36b18ac6f4c0fe6c9cf1ffeb8af9 100644 (file)
--- a/src/math/linreg/coefficient.c
+++ b/src/math/linreg/coefficient.c
@@ -60,6 +60,7 @@ pspp_linreg_coeff_init (pspp_linreg_cache * c, struct design_matrix *X)
   struct pspp_linreg_coeff *coeff;
 
   c->coeff = xnmalloc (X->m->size2 + 1, sizeof (*c->coeff));
+  c->coeff->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. */
@@ -137,7 +138,8 @@ pspp_linreg_coeff_get_n_vars (struct pspp_linreg_coeff *c)
 }
 
 /*
-  Which variable does this coefficient match?
+  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)

diff --git a/src/math/linreg/coefficient.h b/src/math/linreg/coefficient.h
index c2c7200c751a7a45edbc311f50bbbfc1323b7935..0dc1a0353943b67e81e1a7bf5d73f4b4a4692874 100644 (file)
--- a/src/math/linreg/coefficient.h
+++ b/src/math/linreg/coefficient.h
@@ -1,23 +1,22 @@
-/* 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.
- */
+/*
+  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.
+*/
 
 
 #ifndef COEFFICIENT_H
@@ -38,84 +37,74 @@ struct design_matrix;
  */
 struct pspp_linreg_coeff
 {
-  double estimate; /* Estimated coefficient. */
-  double std_err; /* Standard error of the estimate. */
-  struct varinfo *v_info;  /* Information pertaining to the
-                             variable(s) associated with this
-                             coefficient.  The calling function
-                             should initialize this value with the
-                             functions in coefficient.c.  The
-                             estimation procedure ignores this
-                             member. It is here so the caller can
-                             match parameters with relevant variables
-                             and values. If the coefficient is
-                             associated with an interaction, then
-                             v_info contains information for multiple
-                             variables.
-                          */
-  int n_vars; /* Number of variables associated with this coefficient.
-                Coefficients corresponding to interaction terms will
-                have more than one variable.
-             */
+  double estimate;             /* Estimated coefficient. */
+  double std_err;              /* Standard error of the estimate. */
+  struct varinfo *v_info;      /* Information pertaining to the variable(s)
+                                  associated with this coefficient.  The
+                                  calling function should initialize this
+                                  value with the functions in coefficient.c.
+                                  The estimation procedure ignores this
+                                  member. It is here so the caller can match
+                                  parameters with relevant variables and
+                                  values. If the coefficient is associated
+                                  with an interaction, then v_info contains
+                                  information for multiple variables. */
+  int n_vars;                  /* Number of variables associated with this
+                                  coefficient. Coefficients corresponding to
+                                  interaction terms will have more than one
+                                  variable. */
 };
 
 
-
-/*
-  Accessor functions for matching coefficients and variables.
- */
-
 void pspp_linreg_coeff_free (struct pspp_linreg_coeff *);
 
 /*
   Initialize the variable and value pointers inside the
   coefficient structures for the linear model.
  */
-void
-pspp_linreg_coeff_init (pspp_linreg_cache *, 
-                       struct design_matrix *);
+void pspp_linreg_coeff_init (pspp_linreg_cache *, struct design_matrix *);
 
 
 void
-pspp_linreg_coeff_set_estimate (struct pspp_linreg_coeff *,
-                               double estimate);
+pspp_linreg_coeff_set_estimate (struct pspp_linreg_coeff *, double estimate);
 
 void
-pspp_linreg_coeff_set_std_err (struct pspp_linreg_coeff *,
-                              double std_err);
+pspp_linreg_coeff_set_std_err (struct pspp_linreg_coeff *, double std_err);
+
+/*
+  Accessor functions for matching coefficients and variables.
+ */
+
 /*
   Return the estimated value of the coefficient.
  */
-double
-pspp_linreg_coeff_get_est (const struct pspp_linreg_coeff *);
+double pspp_linreg_coeff_get_est (const struct pspp_linreg_coeff *);
 
 /*
   Return the standard error of the estimated coefficient.
 */
-double 
-pspp_linreg_coeff_get_std_err (const struct pspp_linreg_coeff *);
+double pspp_linreg_coeff_get_std_err (const struct pspp_linreg_coeff *);
 
 /*
   How many variables are associated with this coefficient?
  */
-int
-pspp_linreg_coeff_get_n_vars (struct pspp_linreg_coeff *);
+int pspp_linreg_coeff_get_n_vars (struct pspp_linreg_coeff *);
 
 /*
-  Which variable does this coefficient match?
+  Which variable does this coefficient match? The int argument is usually
+  0, unless the coefficient refers to an interaction.
  */
-const struct variable *
-pspp_linreg_coeff_get_var (struct pspp_linreg_coeff *, int );
-
-/* 
-   Which value is associated with this coefficient/variable comination? 
-*/
-const union value *
-pspp_linreg_coeff_get_value (struct pspp_linreg_coeff *,
-                            const struct variable *);
-
-const struct pspp_linreg_coeff *
-pspp_linreg_get_coeff (const pspp_linreg_cache *,
-                      const struct variable *,
-                      const union value *);
+const struct variable *pspp_linreg_coeff_get_var (struct pspp_linreg_coeff *,
+                                                 int);
+/*
+  Which value is associated with this coefficient/variable comination?
+ */
+const union value *pspp_linreg_coeff_get_value (struct pspp_linreg_coeff *,
+                                               const struct variable *);
+
+const struct pspp_linreg_coeff *pspp_linreg_get_coeff (const pspp_linreg_cache
+                                                      *,
+                                                      const struct variable
+                                                      *,
+                                                      const union value *);
 #endif

diff --git a/src/math/linreg/linreg.c b/src/math/linreg/linreg.c
index a5d0936597d7bac275149b08490fb9487d798cb7..ab85e795c93f0c7bb1f9fbc00a11c38c612b9f35 100644 (file)
--- a/src/math/linreg/linreg.c
+++ b/src/math/linreg/linreg.c
@@ -87,6 +87,53 @@ linreg_mean_std (gsl_vector_const_view v, double *mp, double *sp, double *ssp)
 
   return GSL_SUCCESS;
 }
+/*
+  Set V to contain an array of pointers to the variables
+  used in the model. V must be at least C->N_COEFFS in length.
+  The return value is the number of distinct variables found.
+ */
+int
+pspp_linreg_get_vars (const void *c_, struct variable **v)
+{
+  const pspp_linreg_cache *c = c_;
+  struct pspp_linreg_coeff *coef = NULL;
+  const struct variable *tmp;
+  int i;
+  int result = 0;
+
+  /*
+    Make sure the caller doesn't try to sneak a variable
+    into V that is not in the model.
+   */
+  for (i = 0; i < c->n_coeffs; i++)
+    {
+      v[i] = NULL;
+    }
+  /*
+    Start at c->coeff + 1 to avoid the intercept.
+   */
+  v[result] = (struct variable *) pspp_linreg_coeff_get_var (c->coeff + 1, 0);
+  result = (v[result] == NULL) ? 0 : 1;
+
+  for (coef = c->coeff + 2; coef < c->coeff + c->n_coeffs; coef++)
+    {
+      tmp = pspp_linreg_coeff_get_var (coef, 0);
+      assert (tmp != NULL);
+      /* Repeated variables are likely to bunch together, at the end
+        of the array. */
+      i = result - 1;
+      while (i >= 0 && (v[i]->index != tmp->index))
+       {
+         i--;
+       }
+      if (i < 0 && result < c->n_coeffs)
+       {
+         v[result] = (struct variable *) tmp;
+         result++;
+       }
+    }
+  return result;
+}
 
 /*
   Allocate a pspp_linreg_cache and return a pointer
@@ -116,7 +163,11 @@ pspp_linreg_cache_alloc (size_t n, size_t p)
    */
   c->method = PSPP_LINREG_SWEEP;
   c->predict = pspp_linreg_predict;
-  c->residual = pspp_linreg_residual; /* The procedure to comput my residuals. */
+  c->residual = pspp_linreg_residual; /* The procedure to compute my
+                                        residuals. */
+  c->get_vars = pspp_linreg_get_vars; /* The procedure that returns
+                                        pointers to model
+                                        variables. */
   c->resid = NULL; /* The variable storing my residuals. */
   c->pred = NULL; /* The variable storing my predicted values. */
 

diff --git a/src/math/linreg/linreg.h b/src/math/linreg/linreg.h
index 7723187a1e7297f99a73e3bc8aec982b24f22740..f0141f809f47f8c72638861197f583da7292a1a9 100644 (file)
--- a/src/math/linreg/linreg.h
+++ b/src/math/linreg/linreg.h
@@ -163,8 +163,13 @@ struct pspp_linreg_cache_struct
                      const union value **,
                      const union value *,
                      const void *, int);
+  /*
+    Returns pointers to the variables used in the model.
+   */
+  int (*get_vars) (const void *, struct variable **);
   struct variable *resid;
   struct variable *pred;
+
 };
 
 typedef struct pspp_linreg_cache_struct pspp_linreg_cache;
@@ -195,4 +200,8 @@ pspp_linreg_predict (const struct variable **, const union value **,
 double
 pspp_linreg_residual (const struct variable **, const union value **,
                      const union value *, const void *, int);
+/*
+  All variables used in the model.
+ */
+int pspp_linreg_get_vars (const void *, struct variable **);
 #endif