Add flexible legend in MATLAB - matlab

Question

I am trying to add a flexible legend (reduce the length of the line and suppress the unnecessary space between the line and the text) to my figure, I used the steps from another post : advanced plotting (legend manipulation) in Matlab, the code it work fine but when I try to show the figure in the full screen after the legend modification, Everything I have done is meaningless.
x = randn(6,20);
figure(2)
hax = gca;
plot(x(1,:),'--k','linewidth',1.5);
hold on;
plot(x(2,:),'b','linewidth',1.5);
% hold on;
plot(x(3,:),'g','linewidth',1.5);
% hold on;
plot(x(4,:),'r','linewidth',1.5);
% hold on;
plot(x(5,:),'c','linewidth',1.5);
% hold on;
plot(x(6,:),':r','linewidth',1.5);
ylabel('states','fontsize',14); xlabel('time(s)','fontsize',10);
%legend('True','SCKS(h1)','SCKS(h2)','SCKS(h3)','SCKS(h4)','DEM',14);
%
% New call "legend"
%
[leg_h,leg_item_h,~,~]=legend('True','SCKS(h1)','SCKS(h2)','SCKS(h3)','SCKS(h4)','DEM',14);
%
% legendshrink(0.8,[]);
%Fig_legend = legend('Taylor','Euler','LLscheme','LLscheme1');
%set(Fig_legend,'FontSize',7)
grid(hax,'on')
% axis(hax,'tight')
set(hax,'box','on','Layer','top');
set(hax,'tickdir','out')
%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% GENERATION OF THE LEGEND %
%%%%%%%%%%%%%%%%%%%%%%%%%%%%
% Define a scale factor fot the lines
line_scale_factor=1.4;
% Define a scale factor fot the lines
text_scale_factor=1.35;
% Get the "Position" of the legend
orig_leg_pos=get(leg_h,'position')
% Get the number on objects in the legend
n_obj=length(leg_item_h);
% Extract the "Line" object
line_obj=leg_item_h(n_obj/3+1:2:n_obj);
% Get the "LineStyle" of each "Line" in the legend
l_style=get(line_obj,'LineStyle')
% Get the "Color" of each "Line" in the legend
l_col=cell2mat(get(line_obj,'color'))
% Get the "XData" and "YData" of the "Lines" in the legend
leg_x_data=cell2mat(get(line_obj,'xdata'))
leg_y_data=cell2mat(get(line_obj,'ydata'))
% Get the handle of the "Text" of the items in the legend
leg_t=leg_item_h(1:n_obj/3)
% Get the "Text" of the items in the legend
str=get(leg_t,'string')
% Get the "Position" of each "Text" item in the legend
tx=cell2mat(get(leg_t,'position'))
% Delete the original legend
delete(leg_h)
% Create an axes with the same position and size of the original legend
ax=axes('position',orig_leg_pos,'xlim',[0 1],'ylim',[0 1], ...
'xtick',[],'ytick',[],'box','on')
hold on
% Add the legend items to the axes
for i=1:n_obj/3
% Add the lines with the original settings (color, style, ...)
plot([leg_x_data(i,1) leg_x_data(i,2)/line_scale_factor],leg_y_data(i,:),'color',l_col(i,:), ...
'linestyle',l_style{i}, ...
'linewidth',1.4)
% Add the text
th(i,:)=text(leg_x_data(i,2)/text_scale_factor,tx(i,2),0,str{i},'fontsize',9, ...
'unit','normalized')
end
% Get the maximun extent of the lagend "Text"
tx_max_ext=max(reshape([th(:).Extent],4,6)');
% Evaluate the axis scaling factor
tx_r_1=tx_max_ext(3)+leg_x_data(i,2)/line_scale_factor
% Get the axes position
axp=ax.Position
% Resize the axes width
ax.Position=[axp(1) axp(2) axp(3)*tx_r_1 axp(4)]

Answer 1

You can achieve your goal by moving the section of the above code that create the "new legend" into a ResizeFcn of the figure.
This allow adequating the size of the axes based legend each time the size of the figure changes.
To do so, you have to modify your code this way:
1) assign a tag to the figure, This will be used in the ResizeFcn to access to the figure:
cf=figure('tag','res_leg')
2) use guidata to store the original legend handles into the figure object
% Set in the FIGURE GUIDATA the legend handles
my_guidata=guidata(cf)
my_guidata.leg_h=leg_h;
my_guidata.leg_item_h=leg_item_h
% Store the GUIDATA data
guidata(cf,my_guidata)
3) Assign the ResizeFcn to the figure
set(cf,'ResizeFcn',['doResizeFcn(''' get(gcf,'tag') ''')'])
4) Define the ResizeFcn
just move the code you have now in the section in the section % GENERATION OF THE LEGEND % in a function named as the ResizeFcn (in this case doResizeFcn)
Make the following update to the above mentioned code (in the order they are in in the code):
4.1) Get the handle of the figure
4.2) Retrie the figure data using guidata
4.3) Check if the figure already contains the axes used in place of the legend; if so, delete it
4.4) Retrie the original legend data using guidata
4.5) Store in the figure guidata the handle of the axes created to replace the original legend
4.6) Store the figure's guidata
In the following the whole updated code - the above described steps are marked in the code as
%%%%%%%%%%%%
% STEP 4.1 %
%%%%%%%%%%%%
Original code for the plotting
x = randn(6,20);
%%%%%%%%%%
% STEP 1 %
%%%%%%%%%%
% Create the FIGURE and assign a TAG to it (to be used by FINDOBJ)
cf=figure('tag','res_leg')
hax = gca;
plot(x(1,:),'--k','linewidth',1.5);
hold on;
plot(x(2,:),'b','linewidth',1.5);
% hold on;
plot(x(3,:),'g','linewidth',1.5);
% hold on;
plot(x(4,:),'r','linewidth',1.5);
% hold on;
plot(x(5,:),'c','linewidth',1.5);
% hold on;
plot(x(6,:),':r','linewidth',1.5);
ylabel('states','fontsize',14); xlabel('time(s)','fontsize',10);
%legend('True','SCKS(h1)','SCKS(h2)','SCKS(h3)','SCKS(h4)','DEM',14);
%
% New call "legend"
%
[leg_h,leg_item_h,~,~]=legend('True','SCKS(h1)','SCKS(h2)','SCKS(h3)','SCKS(h4)','DEM',14);
%
% legendshrink(0.8,[]);
%Fig_legend = legend('Taylor','Euler','LLscheme','LLscheme1');
%set(Fig_legend,'FontSize',7)
grid(hax,'on')
% axis(hax,'tight')
set(hax,'box','on','Layer','top');
set(hax,'tickdir','out')
%%%%%%%%%%
% STEP 2 %
%%%%%%%%%%
% Set in the FIGURE GUIDATA the legend handles
my_guidata=guidata(cf)
my_guidata.leg_h=leg_h;
my_guidata.leg_item_h=leg_item_h
% Store the GUIDATA data
%%%%%%%%%%
% STEP 3 %
%%%%%%%%%%
guidata(cf,my_guidata)
%%%%%%%%%%
% STEP 4 %
%%%%%%%%%%
% Assign a RESIZE function the the figure
set(cf,'ResizeFcn',['doResizeFcn(''' get(gcf,'tag') ''')'])
Figure's ResizeFnc
function doResizeFcn(str)
%%%%%%%%%%%%
% STEP 4.1 %
%%%%%%%%%%%%
% Get the handle of the calling FIGURE
curr_fig=findobj('tag',str);
%%%%%%%%%%%%
% STEP 4.2 %
%%%%%%%%%%%%
% Retrieve the GUIDATA
my_guidata=guidata(curr_fig)
%%%%%%%%%%%%
% STEP 4.3 %
%%%%%%%%%%%%
% Check if the RESIZE function has been already called
if(isfield(my_guidata,'ax'))
% if so, delete the previously created axes (used in place of the
% legend)
delete(my_guidata.ax)
end
%%%%%%%%%%%%
% STEP 4.4 %
%%%%%%%%%%%%
% Get the old legend handles to retrieve the original legend data
leg_h=my_guidata.leg_h;
leg_item_h=my_guidata.leg_item_h
line_scale_factor=1.4;
% Define a scale factor fot the lines
text_scale_factor=1.35;
% Get the "Position" of the legend
orig_leg_pos=get(leg_h,'position')
% Get the number on objects in the legend
n_obj=length(leg_item_h);
% Extract the "Line" object
line_obj=leg_item_h(n_obj/3+1:2:n_obj);
% Get the "LineStyle" of each "Line" in the legend
l_style=get(line_obj,'LineStyle')
% Get the "Color" of each "Line" in the legend
l_col=cell2mat(get(line_obj,'color'))
% Get the "XData" and "YData" of the "Lines" in the legend
leg_x_data=cell2mat(get(line_obj,'xdata'))
leg_y_data=cell2mat(get(line_obj,'ydata'))
% Get the handle of the "Text" of the items in the legend
leg_t=leg_item_h(1:n_obj/3)
% Get the "Text" of the items in the legend
str=get(leg_t,'string')
% Get the "Position" of each "Text" item in the legend
tx=cell2mat(get(leg_t,'position'))
% Delete the original legend
% % % delete(leg_h)
leg_h.Visible='off'
% Create an axes with the same position and size of the original legend
ax=axes('position',orig_leg_pos,'xlim',[0 1],'ylim',[0 1], ...
'xtick',[],'ytick',[],'box','on')
%%%%%%%%%%%%
% STEP 4.5 %
%%%%%%%%%%%%
% Store in the FIGURE GUIDATA the axes handle
my_guidata.ax=ax;
%%%%%%%%%%%%
% STEP 4.6 %
%%%%%%%%%%%%
% Store the FIGURE GUIDATA
guidata(curr_fig,my_guidata)
hold on
% Add the legend items to the axes
for i=1:n_obj/3
% Add the lines with the original settings (color, style, ...)
plot([leg_x_data(i,1) leg_x_data(i,2)/line_scale_factor],leg_y_data(i,:),'color',l_col(i,:), ...
'linestyle',l_style{i}, ...
'linewidth',1.4)
% Add the text
th(i,:)=text(leg_x_data(i,2)/text_scale_factor,tx(i,2),0,str{i},'fontsize',9, ...
'unit','normalized')
end
% Get the maximun extent of the lagend "Text"
tx_max_ext=max(reshape([th(:).Extent],4,6)');
% Evaluate the axis scaling factor
tx_r_1=tx_max_ext(3)+leg_x_data(i,2)/line_scale_factor
% Get the axes position
axp=ax.Position
% Resize the axes width
ax.Position=[axp(1) axp(2) axp(3)*tx_r_1 axp(4)]
end
Hope this helps,
Qapla'