/* PSPP - a program for statistical analysis.
   Copyright (C) 2005 Free Software Foundation, Inc.

   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 3 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, see <http://www.gnu.org/licenses/>. */

/*
  Functions and data structures to recode categorical variables into
  vectors and sub-rows of matrices.

  To fit many types of statistical models, it is necessary
  to change each value of a categorical variable to a vector with binary
  entries. These vectors are then stored as sub-rows within a matrix
  during model-fitting. We need functions and data strucutres to,
  e.g., map a value, say 'a', of a variable named 'cat_var', to a
  vector, say (0 1 0 0 0), and vice versa.  We also need to be able
  to map the vector back to the value 'a', and if the vector is a
  sub-row of a matrix, we need to know which sub-row corresponds to
  the variable 'cat_var'.

 */

#ifndef CATEGORY_H
#define CATEGORY_H
#include <stdbool.h>
#include <stddef.h>

struct cat_vals;
struct variable ;
union value;

void cat_stored_values_create (const struct variable *);
void cat_stored_values_destroy (struct cat_vals *);

size_t cat_value_find (const struct variable *, const union value *);

const union value *cat_subscript_to_value (const size_t,
					   const struct variable *);


void cat_value_update (const struct variable *, const union value *);

/*
  Return the count for the sth category.
*/
size_t
cat_get_category_count (const size_t, const struct variable *);

/*
  Return the number of categories of a categorical variable.
 */
size_t  cat_get_n_categories (const struct variable *v);

/*
  If VAR is categorical with d categories, its first category should
  correspond to the origin in d-dimensional Euclidean space.
 */
bool cat_is_origin (const struct variable *, const union value *);
#endif