From 924ffe508027894ba8b71d4696794f992efb1b02 Mon Sep 17 00:00:00 2001
From: Allin Cottrell <cottrell@wfu.edu>
Date: Thu, 23 Jan 2025 10:57:23 -0500
Subject: [PATCH] a little more on dataset addobs, for panel data in particular

---
 lib/src/dataset.c     | 25 +++++++++++++++++++------
 lib/src/gretl_panel.c | 28 ++++++++++++++++++++++++++++
 lib/src/gretl_panel.h |  2 ++
 3 files changed, 49 insertions(+), 6 deletions(-)

diff --git a/lib/src/dataset.c b/lib/src/dataset.c
index dd236bd06..6c37b7a1f 100644
--- a/lib/src/dataset.c
+++ b/lib/src/dataset.c
@@ -985,6 +985,7 @@ static void maybe_extend_dummies (DATASET *dset, int oldn)
 static void maybe_extend_indices (DATASET *dset, int oldn)
 {
     int minval, incr;
+    int udone = 0;
     int i, t;
 
     for (i=1; i<dset->v; i++) {
@@ -996,8 +997,16 @@ static void maybe_extend_indices (DATASET *dset, int oldn)
                     dset->Z[i][t] = dset->Z[i][t-1] + incr;
                 }
 	    }
+        } else if (!udone && is_panel_unit_var(dset, i, oldn)) {
+	    for (t=oldn; t<dset->n; t++) {
+                if (t % dset->pd == 0) {
+                    dset->Z[i][t] = dset->Z[i][t-1] + 1;
+                } else {
+                    dset->Z[i][t] = dset->Z[i][t-1];
+                }
+	    }
+            udone = 1;
         }
-        /* FIXME unit index */
     }
 }
 
@@ -3348,23 +3357,27 @@ static int add_obs (DATASET *dset, int n, gretlopt opt, PRN *prn)
         if (opt & OPT_T) {
             /* extending the time dimension */
             err = panel_dataset_extend_time(dset, n, opt | OPT_A);
-            if (!err) {
+            if (!err && gretl_messages_on()) {
                 pprintf(prn, _("Panel time extended by %d observations"), n);
                 pputc(prn, '\n');
             }
         } else {
             err = real_dataset_add_observations(dset, n * dset->pd, OPT_A);
             if (!err) {
-                pprintf(prn, _("Dataset extended by %d units"), n);
-                pputc(prn, '\n');
+                if (gretl_messages_on()) {
+                    pprintf(prn, _("Dataset extended by %d units"), n);
+                    pputc(prn, '\n');
+                }
                 extend_function_sample_range(n * dset->pd);
             }
         }
     } else {
 	err = real_dataset_add_observations(dset, n, OPT_A);
 	if (!err) {
-	    pprintf(prn, _("Dataset extended by %d observations"), n);
-	    pputc(prn, '\n');
+            if (gretl_messages_on()) {
+                pprintf(prn, _("Dataset extended by %d observations"), n);
+                pputc(prn, '\n');
+            }
 	    extend_function_sample_range(n);
 	}
     }
diff --git a/lib/src/gretl_panel.c b/lib/src/gretl_panel.c
index 6caa1301c..a82689920 100644
--- a/lib/src/gretl_panel.c
+++ b/lib/src/gretl_panel.c
@@ -7335,6 +7335,12 @@ int plausible_panel_time_var (const DATASET *dset)
     return ret;
 }
 
+/* Tests whether the series with index number @v codes for the
+   time dimension of a panel dataset. If so, returns 1 and
+   records the minimum value and (constant) increment of the
+   index; otherwise returns 0.
+*/
+
 int is_panel_time_var (const DATASET *dset, int v,
                        int tmax, int *minval,
                        int *incr)
@@ -7371,7 +7377,29 @@ int is_panel_time_var (const DATASET *dset, int v,
     return ret;
 }
 
+int is_panel_unit_var (const DATASET *dset, int v, int tmax)
+{
+    const double *x = dset->Z[v];
+    int t, ret = 1;
+
+    if (x[0] != 1) {
+        return 0;
+    }
+
+    for (t=1; t<tmax && ret; t++) {
+        if (na(x[t]) || x[t] < 0 || x[t] != floor(x[t])) {
+            ret = 0;
+        } else if (t % dset->pd == 0) {
+            if (x[t] != x[t-1] + 1) {
+                ret = 0;
+            }
+        } else if (x[t] != x[t-1]) {
+            ret = 0;
+        }
+    }
 
+    return ret;
+}
 
 /* FIXME: this does not yet handle the dropping of instruments */
 
diff --git a/lib/src/gretl_panel.h b/lib/src/gretl_panel.h
index 4a9a44e42..10f60f1b8 100644
--- a/lib/src/gretl_panel.h
+++ b/lib/src/gretl_panel.h
@@ -73,6 +73,8 @@ int is_panel_time_var (const DATASET *dset, int v,
                        int tnax, int *minval,
                        int *incr);
 
+int is_panel_unit_var (const DATASET *dset, int v, int tmax);
+
 int panel_isconst (int t1, int t2, int pd, const double *x,
 		   int bygroup);