reporting: support horizontal lines

@report_series/report_series.m

@@ -48,6 +48,7 @@ o.graphMarkerSize = 1;
 
 o.graphMiscTikzAddPlotOptions = '';
 
+o.graphHline = {};
 o.graphVline = dates();
 
 o.tableShowMarkers = false;

@report_series/writeSeriesForGraph.m

@@ -30,7 +30,7 @@ function o = writeSeriesForGraph(o, fid, xrange)
 % along with Dynare.  If not, see <http://www.gnu.org/licenses/>.
 
 %% Validate options provided by user
-if isempty(o.graphVline)
+if isempty(o.graphVline) && isempty(o.graphHline)
     assert(~isempty(o.data) && isa(o.data, 'dseries'), ['@report_series.writeSeriesForGraph: must ' ...
                         'provide data as a dseries']);
 end
@@ -68,13 +68,15 @@ assert(~(strcmp(o.graphLineStyle, 'none') && isempty(o.graphMarker)), ['@report_
 
 % Validate graphVline
 assert(isdates(o.graphVline), '@report_series.writeSeriesForGraph: graphVline must be a dates');
+assert(isempty(o.graphHline) || isnumeric(o.graphHline), ...
+       '@report_series.writeSeriesForGraph: graphHline must a single numeric value');
 
 % Zero tolerance
 assert(isfloat(o.zeroTol), '@report_series.write: zeroTol must be a float');
 
 %% graphVline
 
-if ~isempty(o.graphVline)
+if ~isempty(o.graphVline) || ~isempty(o.graphHline)
     for i=1:o.graphVline.ndat
         fprintf(fid, '%%vline %d\n\\begin{pgfonlayer}{background1}\n\\draw[color=%s,%s,line width=%fpt,line join=round',...
                 i, o.graphLineColor, o.graphLineStyle, o.graphLineWidth);
@@ -97,6 +99,27 @@ if ~isempty(o.graphVline)
                       'cs:%d,\\pgfkeysvalueof{/pgfplots/ymax});\n\\end{pgfonlayer}\n'], ...
                 x, x);
     end
+
+    if ~isempty(o.graphHline)
+        fprintf(fid, '%%hline %d\n\\begin{pgfonlayer}{background1}\n\\draw[color=%s,%s,line width=%fpt,line join=round',...
+                i, o.graphLineColor, o.graphLineStyle, o.graphLineWidth);
+        if ~isempty(o.graphMarker)
+            if isempty(o.graphMarkerEdgeColor)
+                o.graphMarkerEdgeColor = o.graphLineColor;
+            end
+        if isempty(o.graphMarkerFaceColor)
+            o.graphMarkerFaceColor = o.graphLineColor;
+        end
+        fprintf(fid, ',mark=%s,mark size=%f,every mark/.append style={draw=%s,fill=%s}',...
+                o.graphMarker,o.graphMarkerSize,o.graphMarkerEdgeColor,o.graphMarkerFaceColor);
+        end
+        if ~isempty(o.graphMiscTikzAddPlotOptions)
+            fprintf(fid, ',%s', o.graphMiscTikzAddPlotOptions);
+        end
+        fprintf(fid, ['] (axis cs:\\pgfkeysvalueof{/pgfplots/xmin},%f) -- (axis ' ...
+                      'cs:\\pgfkeysvalueof{/pgfplots/xmax},%f);\n\\end{pgfonlayer}\n'], ...
+                o.graphHline, o.graphHline);
+    end
     return
 end