Live line plotting over a surface/mesh/imagesc plot.

Question

Feri 2020-3-4

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/509060-live-line-plotting-over-a-surface-mesh-imagesc-plot

评论： Feri 2020-3-12

Hello,

I have a matrix (size 1000x1000) of height values, that I can view with mesh command. From the same figure (that mesh is displayed) I use ginput to the get the coordinates of the mouse and based on the coordinates I can plot the horizontal and vertical line profiles:

[x y] = ginput(1);
figure(2)
subplot(2, 1, 1)
set(gcf, 'Units', 'Inches', 'Position', [5, 5, 10, 3], 'PaperUnits', 'Inches', 'PaperSize', [16, 9.0])
plot(Zp(:, round(x(1))), 'b-'); title('Vertical'); grid on
subplot(2, 1, 2);
plot(Zp(round(y(1)), :), 'k-'); title('Horizontal'); 

Now, what I really need is a live line profile plotting, so as I drag the mouse over the mesh figure I can see the two line profiles.

It is like continuously updating the values of x(1) and y(1) and updating figure(2).

Is it even possible? And if so, could anyone guide me with how to do it?

Thanks.

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Adam Danz 2020-3-10

在 MATLAB Online 中打开

I think you'll have to reconsider how the user will interact with the data to select which column and row will be plotted. The data you describe (1000x1000) has 1 million coordinates and the graphic updates won't keep up with a smoothly moving mouse.

Here's a demo the shows this problem. The data is 30x30 (see 1st line of code) and the mouseMove function only does two simple things 1) updates the title of the axis and 2) shows crosshairs. Copy it to a new m-file and run it.

As you can see, it runs fairly smoothly.

Now, change the first line to data = randi(100,1000,1000); to match your data size and run it again. You'll have to leave the mouse in place for quite a long time to allow the graphics to update to the new mouse position.

data = randi(100,30,30); 
ax = gca() ;  
mesh(ax, data)
view(ax, 2)      % assumed
axis(ax,'tight') % required
xl = xline(min(xlim(ax)), 'k-');
yl = yline(min(ylim(ax)), 'k-');
set(gcf,'windowbuttonmotionfcn', {@mouseMove, data, xl, yl, ax});
function mouseMove(object, eventdata, data, xl, yl, ax)
% Get mouse coordinate
C = get(gca, 'CurrentPoint');
x = round(C(1,1));
y = round(C(1,2));
% If mouse isn't on axis, do nothing.
if x < ax.XLim(1) || x > ax.XLim(2) || y < ax.YLim(1) || y > ax.YLim(2) 
    return
end
% Update crosshairs
xl.Value = x; 
yl.Value = y; 
% plot((1:length(Zp)),  Zp(round(y), :), '.');
title(gca, ['(X,Y) = (', num2str(x), ', ',num2str(y), ')']);
end

Feri 2020-3-11

编辑：Feri 2020-3-11

I got it, was finally able to pass the correct values to the axes, great.

Thanks a million Adam.

How do I make this as the Accepted Answer?

Adam Danz 2020-3-11

编辑：Adam Danz 2020-3-11

Using imagesc makes much more sense. See the demo below.

Note that this solution merely updates values of the line objects rather than replotting lines. This is much faster and more efficient than replotting lines.

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Answer 1

Adam Danz 2020-3-11

3
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/509060-live-line-plotting-over-a-surface-mesh-imagesc-plot#answer_419673

编辑：Adam Danz 2020-3-12

在 MATLAB Online 中打开

Here's a functional demo that uses the WindowButtonMotionFcn property of a figure to capture the mouse position which is used to detect the closest (x,y) coordinates to the mouse within the axes. It continually updates a set of crosshairs that display the coordinates and updates two subplots showing the values along the selected row and column.

See inline comments for details.

Create the data and set up the plot

% Create data
data = peaks(1000); 
% Plot data in main axis
ax(1) = subplot(4,1,[1,2]); 
imagesc(ax(1), data)
ax(1).YDir = 'Normal'; 
axis(ax(1),'equal')
axis(ax(1),'tight') %required!
ax(1).Parent.WindowState = 'Maximized';  % maximize figure
ax(1).Toolbar.Visible = 'off'; % otherwise, toolbar may hide axis title
xlabel(ax(1), 'x axis lable')
ylabel(ax(1), 'y axis lable')
title(ax(1), 'Data')
% Set up cross hairs at axis edges
gobj(1) = xline(min(xlim(ax(1))), 'k-');
gobj(2) = yline(min(ylim(ax(1))), 'k-');
% Set up subplot 2; do all formatting here
ax(2) = subplot(4,1,3); 
gobj(3) = plot(ax(2), 1:size(data,2), nan(1,size(data,2)), '-ko', 'MarkerSize', 4);
xlabel(ax(2), 'x index')
ylabel(ax(2), 'x value')
axis(ax(2), 'tight')
% Set up subplot 3; do all formatting here
ax(3) = subplot(4,1,4); 
gobj(4) =  plot(ax(3), 1:size(data,1), nan(1,size(data,1)), '-ko', 'MarkerSize', 4);
xlabel(ax(3), 'y index')
ylabel(ax(3), 'y value')
axis(ax(3), 'tight')
% After values are set above, assign windowbuttonmotion fcn
set(ax(1).Parent,'windowbuttonmotionfcn', {@mouseMove, data, ax, gobj});

Define the WindowButtonMotionFcn

function mouseMove(~, ~, data, ax, gobj)
% gobj(1) is xline
% gobj(2) is yline
% gobj(3) is subplot 2 line
% gobj(4) is subplot 3 line
% ax is a vector of subplot handles from top to bottom
% data is the imagesc data
% Get mouse coordinate, round to nearest integer.
C = ax(1).CurrentPoint;
x = round(C(1,1));
y = round(C(1,2));
% If mouse isn't on axis, do nothing.
if x < ax(1).XLim(1) || x > ax(1).XLim(2) || y < ax(1).YLim(1) || y > ax(1).YLim(2) 
    return
end
% Update crosshairs
gobj(1).Value = x; 
gobj(1).Label = x; 
gobj(2).Value = y; 
gobj(2).Label = y; 
% Update main title
% title(ax(1), sprintf('(x,y) = (%d, %d)', x, y)); 
% Update x-subplot
gobj(3).YData = data(x,:); 
title(ax(2), sprintf('X = %d', x))
% Update y-subplot
gobj(4).YData = data(:,y); 
title(ax(3), sprintf('Y = %d', y))
end

Addendum: turn on/off interactivity

Press the left mouse button to turn on interactivity and the right mouse button to pause it so that the crosshairs and subplots do not update with mouse motion.

%% Add this section to the first block of code where the figure is created.
% Remove the windowbuttonmotionfcn in that section. 
WindowButtonMotionFcnInput = {@mouseMove, data, ax, gobj}; 
set(ax(1).Parent,'windowbuttondownfcn', {@startStopMouseMove, WindowButtonMotionFcnInput})
%% This function responds to mouse clicks and either assigns 
% or removes the windowbuttonmotionfcn
function startStopMouseMove(hobj,~,WindowButtonMotionFcnInput)
buttonID = hobj.SelectionType; 
switch buttonID
    case 'normal'  %left mouse button
        % Start interactivity
        set(hobj,'windowbuttonmotionfcn', WindowButtonMotionFcnInput);
    case 'alt'     % right mouse button
        % Stop interactivity
        set(hobj,'windowbuttonmotionfcn', []);
end
end

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Adam Danz 2020-3-12

See addendum in answer.

Feri 2020-3-12

Thanks a million :)

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Live line plotting over a surface/mesh/imagesc plot.

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Live line plotting over a surface/mesh/imagesc plot.

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