Categorical dependent variables for EXPORTed models

[pspp] / src / regression_export.h

diff --git a/src/regression_export.h b/src/regression_export.h
index e7f880e331d4409f5b0a688aa6e3edca777a3456..a9583d7bf0b68402fed44d3176f338cd549f17d9 100644 (file)
--- a/src/regression_export.h
+++ b/src/regression_export.h
@@ -115,4 +115,33 @@ const char reg_export_prediction_interval_3[] = " + pspp_reg_variance (var_vals,
 "\n\tresult *= pspp_reg_t_quantile ((1.0 + p) / 2.0);\n\t"
 "result += pspp_reg_estimate (var_vals, var_names);\n\treturn result;\n}\n";
 
+/*
+  Change categorical values to binary vectors. The routine will use
+  an encoding in which a categorical variable with n values is mapped
+  to a vector with n-1 entries. Value 0 is mapped to the zero vector,
+  value 1 is mapped to a vector whose first entry is 1 and all others are
+  0, etc. For example, if a variable can have 'a', 'b' or 'c' as values,
+  then the value 'a' will be encoded as (0,0), 'b' as (1,0) and 'c' as
+  (0,1). If the design matrix used to create the model used a different
+  encoding, then the function pspp_reg_categorical_encode () will return
+  a vector which does not match its categorical value in the model.
+ */
+const char reg_export_categorical_encode_1[] = "struct pspp_reg_categorical_variable\n"
+"{\n\tchar * name;\n\tsize_t n_vals;\n\tchar *values[1024];\n};\n\n"
+"/*\n   This function returns the binary vector which corresponds to the value\n"
+"   of the categorical variable stored in 'value'. The name of the variable is\n"
+"   stored in the 'var' argument. Notice the values stored in the\n"
+"   pspp_categorical_variable structures all end with a space character.\n"
+"   That means the values of the categorical variables you pass to any function\n"
+"   in this program should also end with a space character.\n*/\n"
+"static\ndouble * pspp_reg_get_value_vector (char *var, char *value)\n{\n\tdouble *result;\n\t"
+"int i;\n\t";
+
+const char reg_export_categorical_encode_2[] = "int v_index = 0;\n\t"
+"while (v_index < n_vars && strcmp (var, varlist[i]->name) != 0)\n\t{\n\t\t"
+"v_index++;\n\t}\n\tresult = (double *) malloc (varlist[v_index]->n_vals * sizeof (*result));\n\t"
+"for (i = 0; i < varlist[v_index]->n_vals; i++)\n\t{\n\t\t"
+"if (strcmp ( (varlist[v_index]->values)[i], value) == 0)\n\t\t{\n\t\t\t"
+"result[i] = 1.0;\n\t\t}\n\t\telse result[i] = 0.0;\n\t}\n\n\t"
+"return result;\n}\n\n";
 #endif