#include <math/interaction.h>
#include <string.h>
#include <xalloc.h>
+#include <unistr.h>
struct interaction_variable
{
int n_vars;
const struct variable **members;
struct variable *intr;
+ size_t n_alpha;
};
struct interaction_value
{
const struct interaction_variable *intr;
- union value *strings; /* Concatenation of the string values in this interaction's value. */
+ union value val; /* Concatenation of the string values in this
+ interaction's value, or the product of a bunch
+ of numeric values for a purely numeric
+ interaction.
+ */
double f; /* Product of the numerical values in this interaction's value. */
};
+/*
+ An interaction_variable has type alpha if any of members have type
+ alpha. Otherwise, its type is numeric.
+ */
struct interaction_variable *
interaction_variable_create (const struct variable **vars, int n_vars)
{
struct interaction_variable *result = NULL;
size_t i;
+ int width = 0;
if (n_vars > 0)
{
result = xmalloc (sizeof (*result));
+ result->n_alpha = 0;
result->members = xnmalloc (n_vars, sizeof (*result->members));
- result->intr = var_create_internal (0);
result->n_vars = n_vars;
for (i = 0; i < n_vars; i++)
{
result->members[i] = vars[i];
+ if (var_is_alpha (vars[i]))
+ {
+ result->n_alpha++;
+ width = 1;
+ }
}
}
+ result->intr = var_create_internal (0, width);
+
return result;
}
-
void interaction_variable_destroy (struct interaction_variable *iv)
{
var_destroy (iv->intr);
free (iv);
}
+/*
+ Get one of the member variables.
+ */
+const struct variable *
+interaction_get_member (const struct interaction_variable *iv, size_t i)
+{
+ return iv->members[i];
+}
+
size_t
-interaction_variable_get_n_vars (const struct interaction_variable *iv)
+interaction_get_n_vars (const struct interaction_variable *iv)
{
return (iv == NULL) ? 0 : iv->n_vars;
}
+size_t
+interaction_get_n_alpha (const struct interaction_variable *iv)
+{
+ return iv->n_alpha;
+}
+
+size_t
+interaction_get_n_numeric (const struct interaction_variable *iv)
+{
+ return (interaction_get_n_vars (iv) - interaction_get_n_alpha (iv));
+}
+
+/*
+ Get the interaction variable itself.
+ */
+const struct variable *
+interaction_get_variable (const struct interaction_variable *iv)
+{
+ return iv->intr;
+}
/*
Given list of values, compute the value of the corresponding
interaction. This "value" is not stored as the typical vector of
interaction_value_create (const struct interaction_variable *var, const union value **vals)
{
struct interaction_value *result = NULL;
+ const struct variable *member;
size_t i;
size_t n_vars;
if (var != NULL)
{
+ uint8_t *val;
+ int val_width = 1;
+
result = xmalloc (sizeof (*result));
result->intr = var;
- n_vars = interaction_variable_get_n_vars (var);
- result->strings = value_create (n_vars * MAX_SHORT_STRING + 1);
+ n_vars = interaction_get_n_vars (var);
+ value_init (&result->val, val_width);
+ val = value_str_rw (&result->val, val_width);
+ val[0] = '\0';
result->f = 1.0;
for (i = 0; i < n_vars; i++)
{
- if (var_is_alpha (var->members[i]))
+ member = interaction_get_member (var, i);
+
+ if (var_is_value_missing (member, vals[i], MV_ANY))
{
- strncat (result->strings->s, vals[i]->s, MAX_SHORT_STRING);
+ value_set_missing (&result->val, MAX_SHORT_STRING);
+ result->f = SYSMIS;
+ break;
}
- else if (var_is_numeric (var->members[i]))
+ else
{
- result->f *= vals[i]->f;
+ if (var_is_alpha (var->members[i]))
+ {
+ int w = var_get_width (var->members[i]);
+ value_resize (result, val_width, val_width + w);
+ u8_strncat (val, value_str (vals[i], w), w);
+ val = value_str_rw (&result->val, val_width);
+ }
+ else if (var_is_numeric (var->members[i]))
+ {
+ result->f *= vals[i]->f;
+ }
}
}
+ if (interaction_get_n_alpha (var) == 0)
+ {
+ /*
+ If there are no categorical variables, then the
+ interaction consists of only numeric data. In this case,
+ code that uses this interaction_value will see the union
+ member as the numeric value. If we were to store that
+ numeric value in result->f as well, the calling code may
+ inadvertently square this value by multiplying by
+ result->val->f. Such multiplication would be correct for an
+ interaction consisting of both categorical and numeric
+ data, but a mistake for purely numerical interactions. To
+ avoid the error, we set result->f to 1.0 for numeric
+ interactions.
+ */
+ result->val.f = result->f;
+ result->f = 1.0;
+ }
}
return result;
}
+const union value *
+interaction_value_get (const struct interaction_value *val)
+{
+ return &val->val;
+}
+
+/*
+ Returns the numeric value of the non-zero entry for the vector
+ corresponding to this interaction. Do not use this function to get
+ the numeric value of a purley numeric interaction. Instead, use the
+ union value * returned by interaction_value_get.
+ */
+double
+interaction_value_get_nonzero_entry (const struct interaction_value *val)
+{
+ if (val != NULL)
+ return val->f;
+ return 1.0;
+}
+
void
interaction_value_destroy (struct interaction_value *val)
{
if (val != NULL)
{
- free (val->strings);
+ size_t n_vars = interaction_get_n_vars (val->intr);
+ int val_width = n_vars * MAX_SHORT_STRING + 1;
+
+ value_destroy (&val->val, val_width);
free (val);
}
}
+/*
+ Return a value from a variable that is an interaction.
+ */
+struct interaction_value *
+interaction_case_data (const struct ccase *ccase, const struct interaction_variable *iv)
+{
+ size_t i;
+ size_t n_vars;
+ const struct variable *member;
+ const union value **vals = NULL;
+
+ n_vars = interaction_get_n_vars (iv);
+ vals = xnmalloc (n_vars, sizeof (*vals));
+
+ for (i = 0; i < n_vars; i++)
+ {
+ member = interaction_get_member (iv, i);
+ vals[i] = case_data (ccase, member);
+ }
+
+ return interaction_value_create (iv, vals);
+}
+
+bool
+is_interaction (const struct variable *var, const struct interaction_variable **iv, size_t n_intr)
+{
+ size_t i;
+ const struct variable *intr;
+
+ for (i = 0; i < n_intr; i++)
+ {
+ intr = interaction_get_variable (iv[i]);
+ if (var_get_dict_index (intr) == var_get_dict_index (var))
+ {
+ return true;
+ }
+ }
+ return false;
+}
+
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