From fa3552144ad6eb4e55ef1a566c4ecd2168af0dbe Mon Sep 17 00:00:00 2001 From: John Darrington Date: Sun, 27 Dec 2009 19:04:59 +0100 Subject: [PATCH] FACTOR: Ensure a non-zero number of factors. Before attempting to perform factor analysis, check that the number of factors is greater than zero. Issue an appropriate warning if this is not the case. --- src/language/stats/factor.c | 26 +++++++++++++++++++------- 1 file changed, 19 insertions(+), 7 deletions(-) diff --git a/src/language/stats/factor.c b/src/language/stats/factor.c index 706e1d0d..72a06640 100644 --- a/src/language/stats/factor.c +++ b/src/language/stats/factor.c @@ -542,6 +542,9 @@ cmd_factor (struct lexer *lexer, struct dataset *ds) PV_NO_DUPLICATE | PV_NUMERIC)) goto error; + if (factor.n_vars < 2) + msg (MW, _("Factor analysis on a single variable is not useful.")); + while (lex_token (lexer) != '.') { lex_match (lexer, '/'); @@ -986,7 +989,7 @@ static void show_factor_matrix (const struct cmd_factor *factor, struct idata *idata, const gsl_matrix *fm) { int i; - const int n_factors = n_extracted_factors (factor, idata); + const int n_factors = idata->n_extractions; const int heading_columns = 1; const int heading_rows = 2; @@ -1205,7 +1208,7 @@ show_explained_variance (const struct cmd_factor * factor, struct idata *idata, if (factor->print & PRINT_EXTRACTION) { - if ( i < n_extracted_factors (factor, idata)) + if (i < idata->n_extractions) { /* Sums of squared loadings */ tab_double (t, c++, i + heading_rows, 0, e_lambda, NULL); @@ -1457,12 +1460,20 @@ do_factor (const struct cmd_factor *factor, struct casereader *r) gsl_eigen_symmv_sort (idata->eval, idata->evec, GSL_EIGEN_SORT_ABS_DESC); #endif + idata->n_extractions = n_extracted_factors (factor, idata); + + if (idata->n_extractions == 0) + { + msg (MW, _("The FACTOR criteria result in zero factors extracted. Therefore no analysis will be performed.")); + goto finish; + } + { const gsl_vector *extracted_eigenvalues = NULL; gsl_vector *initial_communalities = gsl_vector_alloc (factor->n_vars); gsl_vector *extracted_communalities = gsl_vector_alloc (factor->n_vars); size_t i; - struct factor_matrix_workspace *fmw = factor_matrix_workspace_alloc (idata->msr->size, n_extracted_factors (factor, idata)); + struct factor_matrix_workspace *fmw = factor_matrix_workspace_alloc (idata->msr->size, idata->n_extractions); gsl_matrix *factor_matrix = gsl_matrix_calloc (factor->n_vars, fmw->n_factors); if ( factor->extraction == EXTRACTION_PAF) @@ -1501,10 +1512,9 @@ do_factor (const struct cmd_factor *factor, struct casereader *r) } else if (factor->extraction == EXTRACTION_PC) { - for (i = 0 ; i < factor->n_vars; ++i) - { - gsl_vector_set (initial_communalities, i, communality (idata, i, factor->n_vars)); - } + for (i = 0; i < factor->n_vars; ++i) + gsl_vector_set (initial_communalities, i, communality (idata, i, factor->n_vars)); + gsl_vector_memcpy (extracted_communalities, initial_communalities); iterate_factor_matrix (analysis_matrix, extracted_communalities, factor_matrix, fmw); @@ -1523,6 +1533,8 @@ do_factor (const struct cmd_factor *factor, struct casereader *r) gsl_vector_free (extracted_communalities); } + finish: + idata_free (idata); casereader_destroy (r); -- 2.30.2