Added a function to clone an interaction.

[pspp-builds.git] / src / math / interaction.c

diff --git a/src/math/interaction.c b/src/math/interaction.c
index afdc3277754884a69fe83b090c2c380321d55935..4e4134f0ffcceb0b1ac79b5a8e0b583a3924be41 100644 (file)
--- a/src/math/interaction.c
+++ b/src/math/interaction.c
@@ -42,20 +42,44 @@
 */
 
 
-
 struct interaction *
 interaction_create (const struct variable *v)
 {
   struct interaction  *i = xmalloc (sizeof *i);
   i->vars = xmalloc (sizeof *i->vars);
-  i->vars[0] = v;
-  i->n_vars = 1;
+  i->n_vars = 0;
+  if ( v )
+    {
+      i->vars[0] = v;
+      i->n_vars = 1;
+    }
   return i;
 }
 
+/* Deep copy an interaction */
+struct interaction *
+interaction_clone (const struct interaction *iact)
+{
+  int v;
+  struct interaction  *i = xmalloc (sizeof *i);
+  i->vars = xcalloc (iact->n_vars, sizeof *i->vars);
+  i->n_vars = iact->n_vars;
+
+  for (v = 0; v < iact->n_vars; ++v)
+    {
+      i->vars[v] = iact->vars[v];
+    }
+
+  return i;
+}
+
+
 void
 interaction_destroy (struct interaction *i)
 {
+  if (NULL == i)
+    return;
+
   free (i->vars);
   free (i);
 }
@@ -68,6 +92,56 @@ interaction_add_variable (struct interaction *i, const struct variable *v)
 }
 
 
+/*
+  Do the variables in X->VARS constitute a proper
+  subset of the variables in Y->VARS?
+ */
+bool
+interaction_is_proper_subset (const struct interaction *x, const struct interaction *y)
+{
+  if (x->n_vars >= y->n_vars)
+    return false;
+
+  return interaction_is_subset (x, y);
+}
+
+/*
+  Do the variables in X->VARS constitute a 
+  subset (proper or otherwise) of the variables in Y->VARS?
+ */
+bool
+interaction_is_subset (const struct interaction *x, const struct interaction *y)
+{
+  size_t i;
+  size_t j;
+  size_t n = 0;
+
+  /* By definition, a subset cannot have more members than its superset */
+  if (x->n_vars > y->n_vars)
+    return false;
+
+  /* Count the number of values which are members of both sets */
+  for (i = 0; i < x->n_vars; i++)
+    {
+      for (j = 0; j < y->n_vars; j++)
+       {
+         if (x->vars [i] == y->vars [j])
+           {
+             n++;
+           }
+       }
+    }
+
+  /* If ALL the members of X were also found in Y, then this must be a subset */    
+  if (n >= x->n_vars)
+    return true;
+
+  return false;
+}
+
+
+
+
 void
 interaction_dump (const struct interaction *i)
 {
@@ -98,10 +172,10 @@ interaction_to_string (const struct interaction *iact, struct string *str)
 }
 
 unsigned int
-interaction_case_hash (const struct interaction *iact, const struct ccase *c)
+interaction_case_hash (const struct interaction *iact, const struct ccase *c, unsigned int base)
 {
   int i;
-  size_t hash = 0;
+  size_t hash = base;
   for (i = 0; i < iact->n_vars; ++i)
     {
       const struct variable *var = iact->vars[i];