/* Resets the state for all the aggregate functions. */
static void
initialize_aggregate_info (struct agr_proc *agr)
{
struct agr_var *iter;
for (iter = agr->agr_vars; iter; iter = iter->next)
{
iter->saw_missing = false;
iter->dbl[0] = iter->dbl[1] = iter->dbl[2] = 0.0;
iter->int1 = iter->int2 = 0;
switch (iter->function)
{
case MIN:
iter->dbl[0] = DBL_MAX;
break;
case MIN | FSTRING:
memset (iter->string, 255, var_get_width (iter->src));
break;
case MAX:
iter->dbl[0] = -DBL_MAX;
break;
case MAX | FSTRING:
memset (iter->string, 0, var_get_width (iter->src));
break;
case MEDIAN:
{
struct caseproto *proto;
struct subcase ordering;
proto = caseproto_create ();
proto = caseproto_add_width (proto, 0);
proto = caseproto_add_width (proto, 0);
if ( ! iter->subject)
iter->subject = dict_create_internal_var (0, 0);
if ( ! iter->weight)
iter->weight = dict_create_internal_var (1, 0);
subcase_init_var (&ordering, iter->subject, SC_ASCEND);
iter->writer = sort_create_writer (&ordering, proto);
subcase_destroy (&ordering);
caseproto_unref (proto);
iter->cc = 0;
}
break;
case SD:
if (iter->moments == NULL)
iter->moments = moments1_create (MOMENT_VARIANCE);
else
moments1_clear (iter->moments);
break;
default:
break;
}
}
}
static void
do_reliability (struct casereader *input, struct dataset *ds,
const struct reliability *rel)
{
int i;
int si;
struct ccase *c;
casenumber n_missing ;
casenumber n_valid = 0;
for (si = 0 ; si < rel->n_sc; ++si)
{
struct cronbach *s = &rel->sc[si];
s->m = xzalloc (sizeof (s->m) * s->n_items);
s->total = moments1_create (MOMENT_VARIANCE);
for (i = 0 ; i < s->n_items ; ++i )
s->m[i] = moments1_create (MOMENT_VARIANCE);
}
input = casereader_create_filter_missing (input,
rel->variables,
rel->n_variables,
rel->exclude,
&n_missing,
NULL);
for (si = 0 ; si < rel->n_sc; ++si)
{
struct cronbach *s = &rel->sc[si];
s->totals_idx = caseproto_get_n_widths (casereader_get_proto (input));
input =
casereader_create_append_numeric (input, append_sum,
s, NULL);
}
for (; (c = casereader_read (input)) != NULL; case_unref (c))
{
double weight = 1.0;
n_valid ++;
for (si = 0; si < rel->n_sc; ++si)
{
struct cronbach *s = &rel->sc[si];
for (i = 0 ; i < s->n_items ; ++i )
moments1_add (s->m[i], case_data (c, s->items[i])->f, weight);
moments1_add (s->total, case_data_idx (c, s->totals_idx)->f, weight);
}
}
casereader_destroy (input);
for (si = 0; si < rel->n_sc; ++si)
{
struct cronbach *s = &rel->sc[si];
s->sum_of_variances = 0;
for (i = 0 ; i < s->n_items ; ++i )
{
double weight, mean, variance;
moments1_calculate (s->m[i], &weight, &mean, &variance, NULL, NULL);
s->sum_of_variances += variance;
}
moments1_calculate (s->total, NULL, NULL, &s->variance_of_sums,
NULL, NULL);
s->alpha =
alpha (s->n_items, s->sum_of_variances, s->variance_of_sums);
}
text_item_submit (text_item_create_format (TEXT_ITEM_PARAGRAPH, _("Scale: %s"),
ds_cstr (&rel->scale_name)));
case_processing_summary (n_valid, n_missing, dataset_dict (ds));
}
