1 /* PSPP - Binary encodings for categorical variables.
2 Copyright (C) 2005 Free Software Foundation, Inc.
4 This program is free software; you can redistribute it and/or
5 modify it under the terms of the GNU General Public License as
6 published by the Free Software Foundation; either version 2 of the
7 License, or (at your option) any later version.
9 This program is distributed in the hope that it will be useful, but
10 WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 General Public License for more details.
14 You should have received a copy of the GNU General Public License
15 along with this program; if not, write to the Free Software
16 Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
20 Functions and data structures to recode categorical variables into
21 vectors and sub-rows of matrices.
23 To fit many types of statistical models, it is necessary
24 to change each value of a categorical variable to a vector with binary
25 entries. These vectors are then stored as sub-rows within a matrix
26 during model-fitting. We need functions and data strucutres to,
27 e.g., map a value, say 'a', of a variable named 'cat_var', to a
28 vector, say (0 1 0 0 0), and vice versa. We also need to be able
29 to map the vector back to the value 'a', and if the vector is a
30 sub-row of a matrix, we need to know which sub-row corresponds to
31 the variable 'cat_var'.
44 void cat_stored_values_create (const struct variable *);
45 void cat_stored_values_destroy (struct cat_vals *);
47 size_t cat_value_find (const struct variable *, const union value *);
49 const union value *cat_subscript_to_value (const size_t,
50 const struct variable *);
53 void cat_value_update (const struct variable *, const union value *);
57 Return the number of categories of a categorical variable.
59 size_t cat_get_n_categories (const struct variable *v);