Multicolumn legend

I would like to be able to create a legend to have a number of columns given (for default the legend function has an unique column in Matlab). In the code written below, for example, I need three columns in the legend so this would have two rows lines and three column lines.

X = 0:pi/100:0.25*pi;
Y1 = sin(X);
Y2 = cos(X);
Y3 = tan(X);
Y4 = 0.5;
fh = figure('toolbar','none','menubar','none','Units','characters');
Pan1 = uipanel(fh,'Units','normalized','Position',[0 0 0.5 1],'title',...
    'Panel1');
Pan2 = uipanel(fh,'Units','normalized','Position',[0.5 0 0.5 1],'title',...
    'Panel2');
haxes = axes('Parent',Pan2,'Units', 'normalized','Position',...
[0.125 0.1 0.75 0.75]);
hplot = plot(haxes,X,Y1,X,Y2,X,Y3,X,Y4);
xlabel(haxes,'Time (second)');
ylabel(haxes,'Amplitude (meter)');
title(haxes,'Trigonometric functions');
Ley = {'Sine function','Cosine function','Tangent function','Constant'};
legend(haxes,Ley,'Location','SouthOutside');

I have tried to use the application called gridlegend on the Matlab File Exchange replacing

legend(haxes,Ley,'Location','SouthOutside');

with

gridLegend(hplot,2,Ley,'Location','SouthOutside');

and

gridLegend(hplot,3,Ley,'Location','SouthOutside');

However, the results obtained are not valid because of the legend's contents appears overlapped and inclusive, for the case 3, is wrong.

P.D. I have tried the columnlegend application in Matlab File Exchange but I need that legend location to be SouthOutside, so it does not work for me.

Answer 1

[Daniel Shub]

MATLAB was not designed to produce publication quality graphs. People have hammered on MATLAB to push its capabilities. If neither columnlegend nor gridlegend can do it, there is likely no easy solution. You need to (1) loosen your constraints (e.g., choose a location other than SouthOutside), (2) be willing to code it your self, (3) create a plot as close as you can and then edit it with a graphics editing program (e.g., Iinkscape or GIMP), or (4) choose a program designed to make nice looking graphs (e.g., Pgfplots).

[Julián Francisco]

@Daniel: Thank you so much for your answer.

[Scott]

"MATLAB was not designed to produce publication quality graphs."

What quality graphs was it designed to produce? Because it's certainly designed to produce graphs.

[Daniel Shub]

@Scott there is a huge difference between software that is designed to produce graphs and one designed to produce publication quality graphs. Think about the difference between MS Word and MS Publisher, both are designed to produce text based documents, but only one is designed to produce publication quality text documents.

Answer 2

[Julián Francisco]

Here is my solution for a legend which has a 'SouthOutside' location (I have supposed that the axes graphic object has 'normalized' units and its 'Position' is [0.1 0.1 0.8 0.8]):

      function CLegend(hax,numcol,Ley)
      %# Inputs
      % hax : handle of the axes object to which belongs the legend
      % numcol: number of columns for the legend
      % Ley: text strings (labels) for the legend

      set(hax,'Units','normalized','Position',[0.1 0.1 0.8 0.8]);
      set(hax,'Units','characters');
      posAx = get(hax,'Position');
      insAx = get(hax,'TightInset');

      [legend_h,object_h] = legend(hax,Ley,'Units','characters','Location',...
          'South','Orientation','vertical');
      posl = get(legend_h,'Position');
      numlines = length(Ley);
      if (numlines<numcol)
          numcol = numlines;
      end

      numpercolumn = ceil(numlines/numcol);

      if (mod(numlines,numpercolumn) == 0)
          numcol = numlines/numpercolumn;
      end

      l = zeros(1,numlines);
      a = zeros(1,numlines);
      h = zeros(1,4);
      for j=1:numlines
          h = get(object_h(j),'Extent');
          l(j) = h(3);
          a(j) = h(4);
          set(object_h(j),'Units','characters');
      end

      lmax = posl(3)*max(l);
      hmax = posl(4)*max(a);
      hLine = object_h(numlines+1);
      xdata = get(hLine, 'xdata');
      dx = xdata(2)-xdata(1);
      di = 2;

      sheight = hmax;     
      height = hmax*numpercolumn-sheight/2;            
      line_width = dx*posl(3);                
      spacer = xdata(1)*posl(3);              
      delta1 = spacer + line_width + spacer + lmax;
      delta2 = line_width + spacer + lmax + spacer;
      delta3 = lmax + spacer + line_width + spacer;
      factx = 1/(posl(3)*numcol);
      facty = 1/(hmax*numpercolumn);
      width_l = numcol*delta1;

      set(legend_h, 'Position', [posAx(1) + 0.5*(posAx(3)-width_l) posl(2) ...
         width_l  numpercolumn*hmax]);

      col_ind = -1;
      row_ind = -1;
      j = 0;
      for i=1:numlines,

          if strcmpi(orient,'horizontal'),
              if mod(i,numcol)==1,
                  row_ind = row_ind+1;
              end
              col_ind = mod(i,numcol)-1;
              if col_ind == -1,
                   col_ind = numcol-1;
              end

          else
              if numpercolumn==1 || mod(i,numpercolumn)==1,
                  col_ind = col_ind+1;
              end

              row_ind = mod(i,numpercolumn)-1;
              if row_ind == -1,
                   row_ind = numpercolumn-1;
              end   
          end

          if (i==1)
              linenum = i+numlines;
          else
              linenum = linenum+di;
          end
          labelnum = i;

          set(object_h(linenum), 'ydata',facty*[height-row_ind*sheight ...
              height-row_ind*sheight]);
          set(object_h(linenum), 'xdata', factx*[spacer + j*delta2 ...
                      spacer + j*delta2 + line_width]);
          set(object_h(linenum+1), 'ydata',facty*(height-row_ind*sheight));
          set(object_h(linenum+1), 'xdata', factx*(spacer+line_width/2));
          set(object_h(labelnum), 'Position', [j*delta3+spacer*2+line_width ...
              height-row_ind*sheight]);
          if (mod(i,numpercolumn)== 0)
              j = j + 1;   
          end
      end
      opl = get(legend_h,'OuterPosition');
      set(hax, 'Position',[posAx(1) posAx(2)+opl(4) posAx(3) posAx(4)-opl(4)]);

      set(legend_h, 'OuterPosition',[opl(1) (posAx(2)-insAx(2))/2 opl(3) opl(4)]);
      set(hax,'Units','normalized');
      end