Cursor line

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

Answer 1

[Matt Fig]

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.

[Mtlb Usr]

Hi Matt,

It's very good!! Although I can't move the datatips that the function has created. These are fixed.

How can I move these data tips at anytime?

regards

[Mtlb Usr]

Hi,

I hadn't realized!!! I can move the datatips with by arrow's key of pc.

I think that with this solution I will resolve my question.

Thank you so much

regards

[Matthias Luh]

This is awesome, thank you! I extended the function a bit and tried to make it more readable for me (see below).

For others looking for help: Also have a look the solution jiro posted here: http://www.mathworks.com/matlabcentral/answers/1758-crosshairs-or-just-vertical-line-across-linked-axis-plots

It might be more intuitive because it allows clicking instead of using the arrow keys.

Dear MATLAB team, if you read this: please add a simple and intuitive crosshair function that can be easily used and activated, e.g. also in the GUI. Something like used in Grafana: https://play.grafana.org/

Extension of Matt Fig's code:

• compatibility with datetime x-axis
• use "shift" + left/right to move around faster
• variable to adjust offset of the textbox relative to data point (textbox_dx_offset, 2x)
• created an own function to generates the text so you only need to adjust it once

function [] = data_subplots_2()
% 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
    subpl(ii) = subplot(3,1,ii);
    pl(ii) = plot(x,sin(x/ii)*ii);
end

% Data tool tip
% https://de.mathworks.com/matlabcentral/answers/1308-cursor-line
textbox_dx_offset = 3;
for ii = 1:length(subpl) % for each subplot
    S.data_x{ii} = get(pl(ii), 'xdata');
    S.data_y{ii} = get(pl(ii), 'ydata');
    S.datalength(ii) = length(S.data_x{ii});    
    S.startindex(ii) = floor(S.datalength(ii) / 2);
    S.delta_x = diff(S.data_x{ii}(S.startindex(ii):(S.startindex(ii) + 1))); % assume uniform x-axis data difference
    S.index(ii) = S.startindex(ii);
    S.text(ii) = text(S.data_x{ii}(S.startindex(ii) + textbox_dx_offset), S.data_y{ii}(S.startindex(ii) + textbox_dx_offset),'here');
    set(S.text(ii), 'string', get_tooltip_text(S, ii), 'parent', subpl(ii), 'BackgroundColor', [1 1 1], 'EdgeColor', [0 0 0]);
    set(subpl(ii), 'nextplot', 'add')
    S.tooltip_point(ii) = plot(subpl(ii), S.data_x{ii}(S.startindex(ii)), S.data_y{ii}(S.startindex(ii)), 'sk');
    set(S.tooltip_point(ii), 'markerfacec', 'b')
end
set(gcf, 'keypressfcn', {@key_press_function, S})

% "on key press" function:
function [] = key_press_function(varargin)
key_id = varargin{2}.Key;
S = varargin{3};
if (size(varargin{2}.Modifier, 2) > 0) && (strcmp(varargin{2}.Modifier{1}, 'shift') == 1)
    dx_fac = 12;
else
    dx_fac = 1;
end
textbox_dx_offset = 3;
if strcmp(key_id, 'leftarrow')
    for ii = 1:length(S.text)
        if S.index(ii) ~= 1
            S.index(ii) = S.index(ii) - dx_fac;
            set(S.tooltip_point(ii), 'xdata', S.data_x{ii}(S.index(ii)),...
                'ydata', S.data_y{ii}(S.index(ii)))
            set(S.text(ii), 'position',...
                [get_text_xpos(S.data_x{ii}(S.index(ii)) + S.delta_x * textbox_dx_offset), S.data_y{ii}(S.index(ii))],...
                'string', get_tooltip_text(S, ii))
        end
    end
elseif strcmp(key_id, 'rightarrow')
    for ii = 1:length(S.text)
        if S.index(ii) ~= S.datalength(ii)
            S.index(ii) = S.index(ii) + dx_fac;
            set(S.tooltip_point(ii),'xdata',S.data_x{ii}(S.index(ii)),...
                'ydata',S.data_y{ii}(S.index(ii)))
            set(S.text(ii),'position',...
                [get_text_xpos(S.data_x{ii}(S.index(ii)) + S.delta_x * textbox_dx_offset), S.data_y{ii}(S.index(ii))],...
                'string', get_tooltip_text(S, ii))
        end
    end
end
set(gcf,'keypressfcn',{@key_press_function,S})  % Update the structure.
% end of  "on key press" function

% "get tooltip text" function:
function text = get_tooltip_text(S, ii)
    if isa(S.data_x{ii}(S.index(ii)), 'datetime') == 1
        text = {...
            ['X: ',sprintf('%s', datestr(S.data_x{ii}(S.index(ii))))];...
            ['Y: ',sprintf('%3.3g', S.data_y{ii}(S.index(ii)))]...
            };
    else
        text = {...
            ['X: ',sprintf('%3.3g', S.data_x{ii}(S.index(ii)))];...
            ['Y: ',sprintf('%3.3g', S.data_y{ii}(S.index(ii)))]...
            };
    end
% end of "get tooltip text" function

% "get x-position" function:
function xpos = get_text_xpos(x_value)
    if isa(x_value, 'datetime') == 1
        ax1 = gca;
        % dx_days = diff(ax1.XLim)/24;
        x_min = ax1.XLim(1);
        xpos = datenum(x_value - x_min);
    else
        xpos = x_value;
    end
% end of "get tooltip text" function

Answer 2

[Brett Shoelson]

I would create a line object for each axes, and use LINKPROP to move them all (i.e., set their x positions) simultaneously. You might also take a look at Brandon Kuczenski's vline on the File Exchange.

Cheers,

Brett

Answer 3

[Jiro Doke]

I posted a similar solution here.

Answer 4

[Paulo Silva]

You might find useful tips inside the ginput function

edit ginput
%this function can be found inside ginput
set(fig,'pointer','fullcrosshair'); %horizontal and vertical cursor lines

[Mtlb Usr]

Hi Paulo,

I don't understand you. How shall I use ginput() to get a cursor line?

If you put an example it would be perfect.

Thanks

regards

[Paulo Silva]

for the cursor lines you just need

set(fig,'pointer','fullcrosshair');

fig is the handle for the figure, you can use gcf instead of fig (fig=figure), gcf give the handle of the current figure

for the cursor position inside the figure you can do

get(gcf,'currentpoint')

for the cursor position inside an axis you can use the ginput, it will give you x,y and the button pressed, that's why I told you to look at the ginput code.

[Mtlb Usr]

Hi,

Now I understand you.

However, I can't see the point or coordinate that I picked by the cursor.

How could I see?

regards

[Paulo Silva]

Here's one example, it allows you to mark points of several subplots, the coordinates and button pressed is shown on the command line.

subplot(311)

hold on

subplot(312)

hold on

subplot(313)

hold on

but=1;

while ((but==1))

[x,y,but]=ginput(1)

plot(x,y,'*')

end

[Paulo Silva]

Another version, now the subplots have different and fixed limits, also the point only gets marked when you press the mouse left button.

subplot(311)

hold on

axis([0 100 -10 10])

subplot(312)

hold on

axis([-100 100 -20 10])

subplot(313)

hold on

axis([100 200 -10 20])

but=1;

while ((but==1))

[x,y,but]=ginput(1)

if but==1

plot(x,y,'*')

end

end

[Paulo Silva]

if you want to save the coordinates pressed

but=1;xv=[];yv=[];

while ((but==1))

[x,y,but]=ginput(1)

if but==1

xv=[xv x];yv=[yv y];

plot(x,y,'*')

end

end

plot(xv,yv) %you can connect the dots marked

[Mtlb Usr]

Hi Paulo,

Your example is near that I want it,but this isn't exactly.

The effect that I need is similar to a data cursor.

Do you understand me?

regards

[Paulo Silva]

I'm finally understanding but what you want isn't easy, at least for me and my basic matlab skills, maybe someone with more experience might help you.

Here's some websites with info, maybe you can find something useful in them

http://matlab.wikia.com/wiki/MATLAB_Wiki

http://undocumentedmatlab.com

[Mtlb Usr]

Hi,

OK, I'm going to visit these web pages.

Thank you

regards