From e210b20bf6f405637c8c03dd280b5a4a627191b8 Mon Sep 17 00:00:00 2001
From: Jason Stover <jhs@math.gcsu.edu>
Date: Thu, 15 Dec 2005 22:23:18 +0000
Subject: [PATCH] Subcommand to export a model as a C function

---
 src/regression.q | 74 ++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 72 insertions(+), 2 deletions(-)

diff --git a/src/regression.q b/src/regression.q
index 30224a62..eced9544 100644
--- a/src/regression.q
+++ b/src/regression.q
@@ -44,7 +44,6 @@
 
 /* (headers) */
 
-
 /* (specification)
    "REGRESSION" (regression_):
    *variables=varlist;
@@ -65,6 +64,7 @@
    f,
    defaults,
    all;
+   export=custom;
    ^dependent=varlist;
    ^method=enter.
 */
@@ -77,6 +77,12 @@ static struct cmd_regression cmd;
  */
 size_t *indep_vars;
 
+/*
+  File where the model will be saved if the EXPORT subcommand
+  is given. 
+ */
+struct file_handle *model_file;
+
 /*
   Return value for the procedure.
  */
@@ -465,6 +471,69 @@ subcommand_statistics (int *keywords, pspp_linreg_cache * c)
   statistics_keyword_output (reg_stats_tol, keywords[tol], c);
   statistics_keyword_output (reg_stats_selection, keywords[selection], c);
 }
+static void
+subcommand_export (int export, pspp_linreg_cache *c)
+{
+  FILE *fp;
+  size_t i;
+  struct pspp_linreg_coeff coeff;
+
+  if (export)
+    {
+      assert (c != NULL);
+      assert (model_file != NULL);
+      assert (fp != NULL);
+      fp = fopen (handle_get_filename (model_file), "w");
+      fprintf (fp, "/* PSPP-generated linear regression model.\n   Copyright (C) 2005 Free Software Foundation, Inc.\n   Generated by the GNU PSPP regression procedure.\n\n   This program is free software; you can redistribute it and/or\n   modify it under the terms of the GNU General Public License as\n   published by the Free Software Foundation; either version 2 of the\n   License, or (at your option) any later version.\n\n   This program is distributed in the hope that it will be useful, but\n   WITHOUT ANY WARRANTY; without even the implied warranty of\n   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU\n   General Public License for more details.\n\n   You should have received a copy of the GNU General Public License\n   along with GNU PSPP; if not, write to the Free Software\n   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA\n   02110-1301, USA. */\n\n");
+      fprintf (fp, "#include <string.h>\n\n");
+      fprintf (fp, "double\npspp_reg_estimate (const double *var_vals, conts char *[] var_names)\n{\n\tchar *model_depvars[%d] = {", c->n_indeps);
+      for (i = 1; i < c->n_indeps; i++)
+	{
+	  coeff = c->coeff[i];
+	  fprintf (fp, "%s,\n\t\t", coeff.v->name);
+	}
+      coeff = c->coeff[i];
+      fprintf (fp, "%s};\n\t", coeff.v->name);
+      fprintf (fp, "double model_coeffs[%d] = {", c->n_indeps);
+      for (i = 1; i < c->n_indeps; i++)
+	{
+	  coeff = c->coeff[i];
+	  fprintf (fp, "%.15e,\n\t\t", coeff.estimate);
+	}
+      coeff = c->coeff[i];
+      fprintf (fp, "%.15e};\n\t", coeff.estimate);
+      coeff = c->coeff[0];
+      fprintf (fp, "double estimate = %.15e\n\t", coeff.estimate);
+      fprintf (fp, "int i;\n\tint j;\n\n\t");
+      fprintf (fp, "for (i = 0; i < %d; i++)\n\t", c->n_indeps);
+      fprintf (fp, "{\n\t\tfor (j = 0; j < %d; j++)\n\t\t", c->n_indeps);
+      fprintf (fp, "{\n\t\t\tif (strcmp (var_names[i], model_names[j]) == 0)\n");
+      fprintf (fp, "\t\t\t{\n\t\t\t\testimate += var_vals[i] * model_coeffs[j];\n");
+      fprintf (fp, "\t\t\t}\n\t\t}\n\t}\n\treturn estimate;\n}\n");
+      fclose (fp);
+    }
+}
+static int
+regression_custom_export (struct cmd_regression *cmd)
+{
+  /* 0 on failure, 1 on success, 2 on failure that should result in syntax error */
+  if (!lex_force_match ('('))
+    return 0;
+  
+  if (lex_match ('*'))
+    model_file = NULL;
+  else 
+    {
+      model_file = fh_parse ();
+      if (model_file == NULL)
+        return 0; 
+    }
+  
+  if (!lex_force_match (')'))
+    return 0;
+
+  return 1;
+}
 
 int
 cmd_regression (void)
@@ -656,8 +725,9 @@ run_regression (const struct casefile *cf, void *cmd_ UNUSED)
   /* 
      Find the least-squares estimates and other statistics.
    */
-    pspp_linreg ((const gsl_vector *) Y, X->m, &lopts, lcache);
+  pspp_linreg ((const gsl_vector *) Y, X->m, &lopts, lcache);
   subcommand_statistics (cmd.a_statistics, lcache);
+  subcommand_export (cmd.sbc_export, lcache);
   gsl_vector_free (Y);
   design_matrix_destroy (X);
   pspp_linreg_cache_free (lcache);
-- 
2.30.2