-/* PSPP - linear regression.
+/* PSPP - binary encodings for categorical variables.
Copyright (C) 2005 Free Software Foundation, Inc.
Written by Jason H Stover <jason@sakla.net>.
02110-1301, USA. */
/*
- Functions and data structures to recode categorical variables into
- vectors and sub-rows of matrices.
+ Functions and data structures to store values of a categorical
+ variable, and to recode those values into binary vectors.
For some 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. E.g., we need functions and data strucutres to map a
+ model-fitting. For example, we need functions and data strucutres to 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'.
-
- The data structures defined here will be placed in the variable
- structure in the future. When that happens, the useful code
- in this file will be that which refers to design matrices.
*/
#include <config.h>
#include <stdlib.h>
#include <error.h>
#include "alloc.h"
#include "error.h"
-#include "var.h"
#include "cat.h"
+#include "cat-routines.h"
#include <string.h>
-#include <math.h>
-#include <gsl/gsl_machine.h>
-#include <gsl/gsl_vector.h>
-#include <gsl/gsl_matrix.h>
#define N_INITIAL_CATEGORIES 1
-#define CAT_COLUMN_NOT_FOUND -1
-#define CAT_VALUE_NOT_FOUND -2
-#define CAT_INDEX_NOT_FOUND -3
void
cat_stored_values_create (struct variable *v)
}
}
-#if 0
-struct recoded_categorical_array *
-cr_recoded_cat_ar_create (int n_variables, struct variable *v_variables[])
-{
- size_t n_categoricals = 0;
- size_t i;
- struct recoded_categorical_array *ca;
- struct variable *v;
-
- ca = xmalloc (sizeof *ca);
- for (i = 0; i < n_variables; i++)
- {
- v = v_variables[i];
- if (v->type == ALPHA)
- {
- n_categoricals++;
- }
- }
- ca->n_vars = n_categoricals;
- ca->a = xnmalloc (n_categoricals, sizeof *ca->a);
- for (i = 0; i < n_categoricals; i++)
- {
- *(ca->a + i) = cr_recoded_categorical_create (v_variables[i]);
- }
-
- return ca;
-}
-
-int
-cr_free_recoded_array (struct recoded_categorical_array *r)
-{
- int rc = 0;
- size_t i;
-
- for (i = 0; i < r->n_vars; i++)
- {
- cr_recoded_categorical_destroy (*(r->a + i));
- }
- return rc;
-}
-#endif
-static size_t
+/*
+ Which subscript corresponds to val?
+ */
+size_t
cat_value_find (const struct variable *v, const union value *val)
{
size_t i;
}
}
-/*
- Create a gsl_matrix, whose rows correspond to values of a
- categorical variable. Since n categories have n-1 degrees of
- freedom, the gsl_matrix is n-by-(n-1), with the first category
- encoded as the zero vector.
- */
-#if 0
-void
-cat_create_value_matrix (struct variable *v)
-{
- size_t i;
- size_t row;
- size_t col;
- size_t n_rows;
- size_t n_cols;
-
- assert (v != NULL);
- if (v->type == ALPHA)
- {
- assert (v->rc != NULL);
- n_rows = v->rc->n_categories;
- n_cols = v->rc->n_categories - 1;
- v->rc->m = gsl_matrix_calloc (n_rows, n_cols);
- for (row = 1; row < n_rows; row++)
- {
- col = row - 1;
- gsl_matrix_set (v->rc->m, row, col, 1.0);
- }
- }
-}
-#endif
-/*
- Return the subscript of the binary vector corresponding
- to this value.
- */
-size_t
-cat_value_to_subscript (const union value *val, struct variable *v)
-{
- const union value *val2;
- size_t subscript;
- int different;
-
- assert (v != NULL);
- assert (val != NULL);
- assert (v->obs_vals != NULL);
- subscript = v->obs_vals->n_categories - 1;
- while (subscript > 0)
- {
- val2 = v->obs_vals->vals + subscript;
- assert (val2 != NULL);
- different = compare_values (val, val2, v->width);
- if (!different)
- {
- return subscript;
- }
- subscript--;
- }
- return subscript;
-}
-
union value *
cat_subscript_to_value (const size_t s, struct variable *v)
{
return NULL;
}
}
-
-#if 0
-/*
- Return the row of the matrix corresponding
- to the value v.
- */
-static gsl_vector_view
-cr_value_to_vector (const union value *v, struct recoded_categorical *cr)
-{
- size_t row;
- row = cr_value_to_subscript (v, cr);
- return gsl_matrix_row (cr->m, row);
-}
-#endif
-/*
- Which element of a vector is equal to the value x?
- */
-static size_t
-cat_which_element_eq (const gsl_vector * vec, double x)
-{
- size_t i;
-
- for (i = 0; i < vec->size; i++)
- {
- if (fabs (gsl_vector_get (vec, i) - x) < GSL_DBL_EPSILON)
- {
- return i;
- }
- }
- return CAT_VALUE_NOT_FOUND;
-}
-static int
-cat_is_zero_vector (const gsl_vector * vec)
-{
- size_t i;
-
- for (i = 0; i < vec->size; i++)
- {
- if (gsl_vector_get (vec, i) != 0.0)
- {
- return 0;
- }
- }
- return 1;
-}
-
-/*
- Return the value corresponding to the vector.
- To avoid searching the matrix, this routine takes
- advantage of the fact that element (i,i+1) is 1
- when i is between 1 and cr->n_categories - 1 and
- i is 0 otherwise.
- */
-union value *
-cr_vector_to_value (const gsl_vector * vec, struct variable *v)
-{
- size_t i;
-
- i = cat_which_element_eq (vec, 1.0);
- if (i != CAT_VALUE_NOT_FOUND)
- {
- return cat_subscript_to_value (i + 1, v);
- }
- if (cat_is_zero_vector (vec))
- {
- return cat_subscript_to_value (0, v);
- }
- return NULL;
-}
-
-#if 0
-/*
- Given a variable, return a pointer to its recoded
- structure. BUSTED IN HERE.
- */
-struct recoded_categorical *
-cr_var_to_recoded_categorical (const struct variable *v,
- struct recoded_categorical_array *ca)
-{
- struct recoded_categorical *rc;
- size_t i;
-
- for (i = 0; i < ca->n_vars; i++)
- {
- rc = *(ca->a + i);
- if (rc->v->index == v->index)
- {
- return rc;
- }
- }
- return NULL;
-}
-#endif
-struct design_matrix *
-design_matrix_create (int n_variables,
- const struct variable *v_variables[],
- const size_t n_data)
-{
- struct design_matrix *dm;
- const struct variable *v;
- size_t i;
- size_t n_cols = 0;
- size_t col;
-
- dm = xmalloc (sizeof *dm);
- dm->vars = xnmalloc (n_variables, sizeof *dm->vars);
- dm->n_vars = n_variables;
-
- for (i = 0; i < n_variables; i++)
- {
- v = v_variables[i];
- assert ((dm->vars + i) != NULL);
- (dm->vars + i)->v = v; /* Allows us to look up the variable from
- the design matrix. */
- (dm->vars + i)->first_column = n_cols;
- if (v->type == NUMERIC)
- {
- n_cols++;
- (dm->vars + i)->last_column = n_cols;
- }
- else if (v->type == ALPHA)
- {
- assert (v->obs_vals != NULL);
- (dm->vars + i)->last_column =
- (dm->vars + i)->first_column + v->obs_vals->n_categories - 2;
- n_cols += v->obs_vals->n_categories - 1;
- }
- }
- dm->m = gsl_matrix_calloc (n_data, n_cols);
- col = 0;
-
- return dm;
-}
-
-void
-design_matrix_destroy (struct design_matrix *dm)
-{
- free (dm->vars);
- gsl_matrix_free (dm->m);
- free (dm);
-}
-
-/*
- Return the index of the variable for the
- given column.
- */
-static size_t
-design_matrix_col_to_var_index (const struct design_matrix *dm, size_t col)
-{
- size_t i;
- struct design_matrix_var v;
-
- for (i = 0; i < dm->n_vars; i++)
- {
- v = dm->vars[i];
- if (v.first_column <= col && col <= v.last_column)
- return (v.v)->index;
- }
- return CAT_INDEX_NOT_FOUND;
-}
-
-/*
- Return a pointer to the variable whose values
- are stored in column col.
- */
-struct variable *
-design_matrix_col_to_var (const struct design_matrix *dm, size_t col)
-{
- size_t index;
- size_t i;
- struct design_matrix_var dmv;
-
- index = design_matrix_col_to_var_index (dm, col);
- for (i = 0; i < dm->n_vars; i++)
- {
- dmv = dm->vars[i];
- if ((dmv.v)->index == index)
- {
- return (struct variable *) dmv.v;
- }
- }
- return NULL;
-}
-
-static size_t
-cmp_dm_var_index (const struct design_matrix_var *dmv, size_t index)
-{
- if (dmv->v->index == index)
- return 1;
- return 0;
-}
-
-/*
- Return the number of the first column which holds the
- values for variable v.
- */
-size_t
-design_matrix_var_to_column (const struct design_matrix * dm,
- const struct variable * v)
-{
- size_t i;
- struct design_matrix_var tmp;
-
- for (i = 0; i < dm->n_vars; i++)
- {
- tmp = dm->vars[i];
- if (cmp_dm_var_index (&tmp, v->index))
- {
- return tmp.first_column;
- }
- }
- return CAT_COLUMN_NOT_FOUND;
-}
-
-/* Last column. */
-static size_t
-dm_var_to_last_column (const struct design_matrix *dm,
- const struct variable *v)
-{
- size_t i;
- struct design_matrix_var tmp;
-
- for (i = 0; i < dm->n_vars; i++)
- {
- tmp = dm->vars[i];
- if (cmp_dm_var_index (&tmp, v->index))
- {
- return tmp.last_column;
- }
- }
- return CAT_COLUMN_NOT_FOUND;
-}
-
-/*
- Set the appropriate value in the design matrix,
- whether that value is from a categorical or numeric
- variable. For a categorical variable, only the usual
- binary encoding is allowed.
- */
-void
-design_matrix_set_categorical (struct design_matrix *dm, size_t row,
- const struct variable *var,
- const union value *val)
-{
- size_t col;
- size_t is_one;
- size_t fc;
- size_t lc;
- double entry;
-
- assert (var->type == ALPHA);
- fc = design_matrix_var_to_column (dm, var);
- lc = dm_var_to_last_column (dm, var);
- assert (lc != CAT_COLUMN_NOT_FOUND);
- assert (fc != CAT_COLUMN_NOT_FOUND);
- is_one = fc + cat_value_find (var, val);
- for (col = fc; col <= lc; col++)
- {
- entry = (col == is_one) ? 1.0 : 0.0;
- gsl_matrix_set (dm->m, row, col, entry);
- }
-}
-void
-design_matrix_set_numeric (struct design_matrix *dm, size_t row,
- const struct variable *var, const union value *val)
-{
- size_t col;
-
- assert (var->type == NUMERIC);
- col = design_matrix_var_to_column ((const struct design_matrix *) dm, var);
- assert (col != CAT_COLUMN_NOT_FOUND);
- gsl_matrix_set (dm->m, row, col, val->f);
-}
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