I tweaked the hggroup patch slightly

diff -r 078c0c4d205d scripts/plot/util/private/__gnuplot_draw_axes__.m
--- a/scripts/plot/util/private/__gnuplot_draw_axes__.m        Sun Oct 16 02:23:54 2016 -0500
+++ b/scripts/plot/util/private/__gnuplot_draw_axes__.m        Sun Oct 16 12:20:34 2016 -0700
@@ -613,7 +613,7 @@ function __gnuplot_draw_axes__ (h, plot_

       case "line"
         if (strcmp (get (obj.parent, "type"), "hggroup"))
-          hg = get (obj.parent, 'children');
+          hg = get (obj.parent, "children");
           if (hg(1) == h_obj && ! isempty (get (obj.parent, "displayname")))
             data_idx += 1;
             is_image_data(data_idx) = false;
@@ -646,7 +646,7 @@ function __gnuplot_draw_axes__ (h, plot_
               withclause{data_idx} = sprintf ("with %s linestyle %d",
                                               errbars, sidx(1));
             else
-              # Place phantom stemseries data for legend
+              ## Place phantom stemseries data for legend
               data{data_idx} = nan (2,1);
               usingclause{data_idx} = sprintf ("record=1 using ($1):($2)");
               hgobj = get (obj.parent);
@@ -1196,9 +1196,9 @@ function __gnuplot_draw_axes__ (h, plot_

       case "surface"
         view_map = true;
-        tspec = "title \"\"";
+        tspec = 'title ""';
         if (! isempty (obj.displayname))
-          # Place phantom line data for approximate legend symbol
+          ## Place phantom line data for approximate legend symbol
           data_idx += 1;
           is_image_data(data_idx) = false;
           parametric(data_idx) = false;

to follow some Octave coding guidelines.

It was applied here http://hg.savannah.gnu.org/hgweb/octave/rev/5ab3c91fc4bb.

Fixed, closing report.

Attached is a fix for the legend entry of some more hggroup objects.  I've done what I can as far as almost-correct legend symbols.  One of gnuplot's limitations is in the area of keys and key entries.  I wish it was done differently however many years ago now.  In order to construct a key with both lines and points, someone devised a new style 'linespoints': sounds good, but it is so restrictive once other styles are introduced, e.g., error bars and boxes, etc.  Then try remember the names.  It would have been much nicer if one could specify "plot <mydata> with lines ... and points ..." such that all of those items appear in the key symbol.

Anyway, try the following:

demo legend 17
demo legend 18
demo legend
demo errorbar

The stem series of legend 17 demo illustrates how a circle and line can be in the key IF the two are the same color.  But linespoints can't have different colors for lines and for points, so those two have to be done separately--hence cannont be in the same key symbol.


(file #38738)

OK, that's me.

Attached is a change to demo 17 which adds a second subplot with another hggroup, stems.  (The error bars hggroup is covered well by the errorbar.m demos.)  I think those are all the hggroup object collections.

The patch doesn't fix anything as far as bugs, but it brings out a couple issues in both OpenGL and gnuplot toolkits.  For OpenGL, the legend placement doesn't seem quite right in subplots and there is an axes border for only one of the subplots.  For gnuplot, the legends are wrong.

By the way, for stems the proper legend graphic is simply the stem marker, is that correct?  There is no other line in the legend like might be done for error bars?

OK, I see this.  There are multiple hggroup regression problems here.  I will find a fix for that on the development branch.

On the stable branch there are a couple of general problems with legend demos that should be fixed beyond the above.  Attached is a fix for a typo in demo 23.

Also, Rik could you have a look at demos 26, 27 and 28:

octave:23> demo legend 26
legend example 26:
 clf;
 x = 0:10;
 y1 = rand (size (x));
 y2 = rand (size (x));
 [ax, h1, h2] = plotyy (x, y1, x, y2);
 title ("plotyy legend test #1: Blue and Green labels");
 legend ([h1, h2], {"Blue", "Green"}, "location", "south");

legend example 26: failed
get: unknown axes property autopos_tag

I see there is extensive use of property 'autopos_tag' in the C++ file "libinterp/corefcn/graphics.cc.  Is this 'autopos_tag' one of the hidden variables that was changes to _autopos_tag_?


(file #38734)

The problem is in line 711 of _gnuplot_draw_axis_, and it is only in the dev branch, because it is caused by
http://hg.savannah.gnu.org/hgweb/octave/rev/54332b6ddeb6 which wasn't applied to the stable branch.