double calc_chi_squared(apop_data *d){
double total = 0;
int n = apop_matrix_sum(d->matrix);
for (int row=0; row <d->matrix->size1; row++)
for (int col=0; col <d->matrix->size2; col++)
total += one_chi_sq(d, row, col, n);
return total;
}
apop_data *kappa_and_pi(apop_data const *tab_in){
apop_data *out = apop_data_alloc();
Apop_stopif(!tab_in, out->error='n'; return out, 0, "NULL input. Returning output with 'n' error code.");
Apop_stopif(!tab_in->matrix, out->error='m'; return out, 0, "NULL input matrix. Returning output with 'm' error code.");
Apop_stopif(tab_in->matrix->size1 != tab_in->matrix->size2, out->error='s'; return out, 0, "Input rows=%zu; input cols=%zu; "
"these need to be equal. Returning output with error code 's'.", tab_in->matrix->size1, tab_in->matrix->size2);
apop_data *tab = apop_data_copy(tab_in);
double total = apop_matrix_sum(tab->matrix);
gsl_matrix_scale(tab->matrix, 1./total);
double p_o = 0, p_e = 0, scott_pe = 0, ia = 0, row_ent = 0, col_ent = 0;
for (int c=0; c< tab->matrix->size1; c++){
double this_obs = apop_data_get(tab, c, c);
p_o += this_obs;
Apop_row_v(tab, c, row);
Apop_col_v(tab, c, col);
double rsum = apop_sum(row);
double csum = apop_sum(col);
p_e += rsum * csum;
scott_pe += pow((rsum+csum)/2, 2);
ia += this_obs * log2(this_obs/(rsum * csum));
row_ent -= rsum * log2(rsum);
col_ent -= csum * log2(csum);
}
apop_data_free(tab);
asprintf(&out->names->title, "Scott's π and Cohen's κ");
apop_data_add_named_elmt(out, "total count", total);
apop_data_add_named_elmt(out, "percent agreement", p_o);
apop_data_add_named_elmt(out, "κ", ((p_e==1)? 0: (p_o - p_e) / (1-p_e) ));
apop_data_add_named_elmt(out, "π", ((p_e==1)? 0: (p_o - scott_pe) / (1-scott_pe)));
apop_data_add_named_elmt(out, "P_I", ia/((row_ent+col_ent)/2));
apop_data_add_named_elmt(out, "Cohen's p_e", p_e);
apop_data_add_named_elmt(out, "Scott's p_e", scott_pe);
apop_data_add_named_elmt(out, "information in agreement", ia);
apop_data_add_named_elmt(out, "row entropy", row_ent);
apop_data_add_named_elmt(out, "column entropy", col_ent);
return out;
}
