MATLAB: Cursor line

2dfigureginputgraphics

Hi,
I've got a figure with several subplots. These subplots are located one under the other one. Then, that I want to do is create a vertical cursor to across all subplots and when I'm going to move this appear the current values of all subplots.
How can I develop this?
thanks
regards

Best Answer

This can be done with a little handle graphics. I don't have time right now to make this code perfect (error checking, special cases handling, commenting(!), etc.), but it should give you something of an idea. Run this function then hit the left and right arrow to see what happens.
function [] = data_subplots()
% Link data cursors so that they track accross subplots.
% Create the subplots.
% Alternatively, use GET to create s and L from existing plots.
x = 1:.1:10;
for ii = 1:3
    s(ii) = subplot(3,1,ii);
    L(ii) = plot(x,sin(x/ii)*ii);
end
% Now start the work.
for ii = 1:length(s)
    S.D{ii} = get(L(ii),{'xdata','ydata'});
    S.L(ii) = length(S.D{ii}{1});    
    S.M(ii) = floor(S.L(ii)/2);
    S.DF = diff(S.D{ii}{1}(S.M(ii):S.M(ii)+1)); % uniform assum
    S.I(ii) = S.M(ii);
    S.T(ii) = text(S.D{ii}{1}(S.M(ii)+2),S.D{ii}{2}(S.M(ii)+2),'here');
    set(S.T(ii),'string',{['X: ',sprintf('%3.3g',S.D{ii}{1}(S.M(ii)))];...
        ['Y: ',sprintf('%3.3g',S.D{ii}{2}(S.M(ii)))]},...
        'parent',s(ii),'backgroundco',[.8 .8 0]);
    set(s(ii),'nextplot','add')
    S.F(ii) = plot(s(ii),S.D{ii}{1}(S.M(ii)),S.D{ii}{2}(S.M(ii)),'sk');
    set(S.F(ii),'markerfacec','b')
end
set(gcf,'keypressfcn',{@fh_kpfcn,S})
function [] = fh_kpfcn(varargin)
D = varargin{2}.Key;
S = varargin{3};
if strcmp(D,'leftarrow')
    for ii = 1:length(S.T)
        if S.I(ii)~=1
            S.I(ii) = S.I(ii)-1;
            set(S.F(ii),'xdata',S.D{ii}{1}(S.I(ii)),...
                'ydata',S.D{ii}{2}(S.I(ii)))
            set(S.T(ii),'position',...
                [S.D{ii}{1}(S.I(ii))+S.DF*2,S.D{ii}{2}(S.I(ii))],...
                'string',{['X: ',sprintf('%3.3g',S.D{ii}{1}(S.I(ii)))];...
                ['Y: ',sprintf('%3.3g',S.D{ii}{2}(S.I(ii)))]})
        end
    end
elseif strcmp(D,'rightarrow')
    for ii = 1:length(S.T)
        if S.I(ii)~=S.L(ii)
            S.I(ii) = S.I(ii)+1;
            set(S.F(ii),'xdata',S.D{ii}{1}(S.I(ii)),...
                'ydata',S.D{ii}{2}(S.I(ii)))
            set(S.T(ii),'position',...
                [S.D{ii}{1}(S.I(ii))+S.DF*2,S.D{ii}{2}(S.I(ii))],...
                'string',{['X: ',sprintf('%3.3g',S.D{ii}{1}(S.I(ii)))];...
                ['Y: ',sprintf('%3.3g',S.D{ii}{2}(S.I(ii)))]})
        end
    end
end
set(gcf,'keypressfcn',{@fh_kpfcn,S})  % Update the structure.
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