From 19da021af9b2acc25d240f58fbce617d72cbdd9e Mon Sep 17 00:00:00 2001
From: mtennekes <mtennekes@gmail.com>
Date: Wed, 8 May 2024 17:56:43 +0200
Subject: [PATCH] improved no-layer case #805

---
 R/messages.R    |  8 ++++++++
 R/step2_data.R  |  2 +-
 R/step3_trans.R |  5 +++--
 R/step4_plot.R  | 43 +++++++++++++++++++++++++++++++++----------
 4 files changed, 45 insertions(+), 13 deletions(-)

diff --git a/R/messages.R b/R/messages.R
index 490e8eec..c75afa95 100644
--- a/R/messages.R
+++ b/R/messages.R
@@ -37,4 +37,12 @@ message_c4a = function(old_palette_name, info) {
 		message(paste0("[cols4all] color palettes: use palettes from the R package cols4all. Run 'cols4all::c4a_gui()' to explore them. The old palette name \"", old_palette_name, "\" is named \"", new2, "\" (in long format \"", new1, "\")"))
 		message_reg(mess)	
 	} 
+}
+
+message_nothing_to_show = function(any_groups) {
+	if (any_groups) {
+		message("[nothing to show] no data layers defined after tm_shape")
+	} else {
+		message("[nothing to show] no layers defined")
+	}
 }
\ No newline at end of file
diff --git a/R/step2_data.R b/R/step2_data.R
index 9b2af815..a2695511 100644
--- a/R/step2_data.R
+++ b/R/step2_data.R
@@ -120,7 +120,7 @@ step2_data = function(tm) {
 				 gp = gp,
 				 tp = tp)
 		})
-		names(lrs) = layernames
+		if (length(lrs)) names(lrs) = layernames
 		
 		shpDT = data.table(shpTM = list(tmg$tms$shpTM))
 		if (dev) timing_add(s2 = "group")
diff --git a/R/step3_trans.R b/R/step3_trans.R
index a367204a..2b14ced9 100644
--- a/R/step3_trans.R
+++ b/R/step3_trans.R
@@ -62,8 +62,9 @@ step3_trans = function(tm) {
 			al[c("trans_dt", "trans_args", "trans_isglobal", "tp")] = NULL
 			al
 		})
-	
-
+		if (!length(adi$layers)) {
+			adi$bbx = tmaptools::bb(shpDT$shpTM[[1]]$shp)
+		}	
 		adi$shpDT = NULL
 
 		adi
diff --git a/R/step4_plot.R b/R/step4_plot.R
index 30647046..647143bb 100644
--- a/R/step4_plot.R
+++ b/R/step4_plot.R
@@ -213,7 +213,15 @@ step4_plot = function(tm, vp, return.asp, show, knit, args) {
 	aux = tm$aux
 	cmp = tm$cmp
 	
+	if ("bbx" %in% names(tmx[[o$main]])) {
+		bbm = tmx[[o$main]]$bbx
+	} else {
+		bbm = NULL
+	}
+	
 	# remove empty data layers
+	any_groups = (length(tmx) > 0L)
+	
 	tmx = lapply(tmx, function(tmxi) {
 		tmxi$layers = lapply(tmxi$layers, function(tml) {
 			empt = vapply(tml$shpDT$shpTM, function(sdt) {
@@ -224,7 +232,7 @@ step4_plot = function(tm, vp, return.asp, show, knit, args) {
 		empt = vapply(tmxi$layers, is.null, logical(1))
 		
 		if (all(empt)) {
-			NULL 
+			NULL
 		} else {
 			tmxi$layers = tmxi$layers[!empt]
 			tmxi
@@ -342,19 +350,34 @@ step4_plot = function(tm, vp, return.asp, show, knit, args) {
 	if (o$legend.only) {
 		d = NULL
 	} else if (any_data_layer) {
-		tmain = tmx[[o$main]][[1]]
-		
 		# create table with meta data for the facets (row, col id, bbox, asp)
 		d = data.table::data.table(do.call(expand.grid, lapply(structure(o$nby, names = c("by1", "by2", "by3")), seq_len)))
 		d[, i := seq_len(nrow(d))]
 		grps = c("by1", "by2", "by3")[o$free.coords]
-		d[, bbox:=do.call(get_bbox, as.list(.SD)), by = grps, .SDcols = c("by1", "by2", "by3")]
-	} else {
-		bbo = o$bbox
-		if (!is.null(bbo)) {
-			bbm = tmaptools::bb(bbo)
+		
+		grp_ids = as.integer(substr(names(tmx), 6, nchar(names(tmx))))
+		if (o$main %in% grp_ids) {
+			tmain = tmx[[which(grp_ids == o$main)]][[1]]
+			d[, bbox:=do.call(get_bbox, as.list(.SD)), by = grps, .SDcols = c("by1", "by2", "by3")]
 		} else {
-			bbm = sf::st_bbox()
+			if (is.null(bbm)) {
+				bbo = o$bbox
+				if (!is.null(bbo)) {
+					bbm = tmaptools::bb(bbo)
+				} else {
+					bbm = sf::st_bbox()
+				}
+			}
+			d[, bbox:=rep(list(bbm),nrow(d))]	
+		}
+	} else {
+		if (is.null(bbm)) {
+			bbo = o$bbox
+			if (!is.null(bbo)) {
+				bbm = tmaptools::bb(bbo)
+			} else {
+				bbm = sf::st_bbox()
+			}
 		}
 		d = data.table::data.table(by1 = 1L, by2 = 1L, by3 = 1L, i = 1, bbox = list(bbm))
 	}
@@ -570,7 +593,7 @@ step4_plot = function(tm, vp, return.asp, show, knit, args) {
 		aux_lid = vapply(aux, function(a) a$lid, FUN.VALUE = numeric(1))
 		
 		if (!any_data_layer && !length(aux_lid)) {
-			message("Nothing to show")
+			message_nothing_to_show(any_groups)
 			return(invisible(NULL))
 		}