I plotted few points using scatter and then label them using text. The position of these labels are same as the position of the points + some offset. Some of these text label overlap with each other and hence I moved them interactively (using mouse). I can check the new position of each of these text individually using property editor. However this is very time-consuming. Is there a better way to get the coordinates of all these text-label?
You can use findobj to get handles to text objects that are children of the current axes (or another handle... your choice):
text_handles = findobj('parent',gca,'type','text');
Then you can get the positions of these text objects:
positions = get(text_handles,'position');
You may need to do a bit more work to associate each text object with its data point - I suggest taking advantage of the property system, perhaps via the UserData field, for this, though there are many options.
If you want to do it easily later do this in your plots, for example:
h=text(2.9,7.5,'MyText');
This will put "MyText" at position 2.9, and 7.5.
Then to change the position use:
set(h,'Position',[2.5 7]);
This will change the position to 2.5 and 7.
Later if you need to see tthe position of text again use:
get(h);
Hope this helps.
Related
I currently use Matlab's imshow to output an image at every iteration of a diffusion filter process, i.e. multiple times per second.
Sometimes during filtering I want a closer look at specific image parts.
However, when using the ('Parent', handle) name-value pair for imshow the magnification and position gets reset.
Is there a way to update the underlying image but having the magnification and position intact?
You can update the cdata in the current axis to your new data matrix which will keep all other settings the same. If this is in a loop, you probably need to call drawnow. E.g:
x=randn(100);
figure;imagesc(x);
Now zoom / pan / do whatever manipulations you want.
f=gca;
x=randn(100);
f.Children.CData = x;
This method of updating of child data is recommended by Matlab as more efficient than destroying the axis child Image and recreating each frame (can't remember the source, it was in one of the help files).
Edit: Just remembered that this syntax won't work on older versions of matlab (pre 2015 or so). In that case, use get/set syntax:
set(get(gca,'Children'),'CData',x);
When we plot a bode/nichols locus, the name of workspace variable is used
tmp=ss(1,1,1,0);
nichols(tmp);
will use 'tmp' as label.
When using more complex data, matlab is using 'untitled1','untitled2',...
tmp={ss(1,1,1,0) , ss(1.2,1,1,0)};
nichols(tmp{:});
How can I change this label programmatically?
Ideally, I'd like a solution working with Matlab 6.5.1, but I'm also interested in solutions restricted to newer versions.
You can modify the labels programmatically via their graphics handles. It looks like the values you want to change are the DisplayName property of some of the children of the current axis. So in your first example, I can change the display name like this:
ch = get(gca,'Children');
set(ch(1),'DisplayName','Fred');
In general, I'm not sure how to predict which children of the current axis are the ones you need to change. For the second example you give, the two curves appear to be the second and third children when I run your code.
Does any one here have an idea about how to change the position of output in the GUI matlab to be to the right side of the box and not in the center ?
i think I have to change some properties of the result text box
Check this post out: Positioning of figures
The figure Position property controls the size and location of the figure window on the screen. Monitor screen size is a property of the root Handle Graphics object. At startup, the MATLAB software determines the size of your computer screen and defines a default value for Position. This default creates figures about one-quarter of the screen's minimum extent and places them centered left to right, in the top half of the screen.
The Position Vector
MATLAB defines the figure Position property as a vector. So you may use a figure and text into it, e.g.
figure(gcf)
text(offsetX1, offsetX1, ['result 1: ' num2str(result1)])
text(offsetX2, offsetX2, ['result 2: ' num2str(result2)])
Displaying analytical results in a MATLAB GUI
This post talks about adding a static textbox with your results and positioning it.
Move GUI figure to specified location on screen:
Syntax:
movegui(h,'position')
movegui(position)
movegui(h)
movegui
The answer is pretty much trying to cover up the vauge nature of the question
I'm trying to annotate a polar plot with data tips labelled with 'R:...,Theta:...' where theta is actually the Greek symbol, rather than the word spelled out. I'm familiar with string formatting using '\theta' resulting in the symbol, but it doesn't work in this case. Is there a way to apply the LaTeX interpreter to data tips? Here's what I have so far:
f1=figure;
t=pi/4;
r=1;
polar(t,r,'.');
dcm_obj = datacursormode(f1);
set(dcm_obj,'UpdateFcn',#polarlabel)
info_struct = getCursorInfo(dcm_obj);
datacursormode on
where polarlabel is defined as follows:
function txt = polarlabel(empt,event_obj)
pos = get(event_obj,'Position');
x=pos(1);
y=pos(2);
[th,r]=cart2pol(x,y);
txt = {['R: ',num2str(r)],...
['\Theta: ',num2str(th*180/pi)]};
Update: This solution is primarily applicable to versions R2014a and older, since it appears to fail for newer versions, specifically R2014b and newer using the new handle graphics system. For newer versions using the new handle graphics system, a solution can be found here.
For some odd reason, the data cursor tool in MATLAB forcibly sets the data tip text to be displayed literally instead of with TeX/LaTeX interpreting (even if the default MATLAB settings say to do so). There also appears to be no way of directly setting text properties via the data cursor mode object properties.
However, I've figured out one workaround. If you add the following to the end of your polarlabel function, the text should display properly:
set(0,'ShowHiddenHandles','on'); % Show hidden handles
hText = findobj('Type','text','Tag','DataTipMarker'); % Find the data tip text
set(0,'ShowHiddenHandles','off'); % Hide handles again
set(hText,'Interpreter','tex'); % Change the interpreter
Explanation
Every graphics object created in the figure has to have a handle. Objects sometimes have their 'HandleVisibility' property set to 'off', so their handles won't show up in the list of child objects for their parent object, thus making them harder to find. One way around this is to set the 'ShowHiddenHandles' property of the root object to 'on'. This will then allow you to use findobj to find the handles of graphics objects with certain properties. (Note: You could also use findall and not worry about the 'ShowHiddenHandles' setting)
Turning on data cursor mode and clicking the plot creates an hggroup object, one child of which is the text object for the text that is displayed. The above code finds this text object and changes the 'Interpreter' property to 'tex' so that the theta symbol is correctly displayed.
Technically, the above code only has to be called once, not every time polarlabel is called. However, the text object doesn't exist until the first time you click on the plot to bring up the data tip (i.e. the first time polarlabel gets called), so the code has to go in the UpdateFcn for the data cursor mode object so that the first data tip displayed has the right text formatting.
I have a question about the values returned by getPosition. Below is my code. It lets the user set 10 points on a given image:
figure ,imshow(im);
colorArray=['y','m','c','r','g','b','w','k','y','m','c'];
pointArray = cell(1,10);
% Construct boundary constraint function
fcn = makeConstrainToRectFcn('impoint',get(gca,'XLim'),get(gca,'YLim'));
for i = 1:10
p = impoint(gca);
% Enforce boundary constraint function using setPositionConstraintFcn
setPositionConstraintFcn(p,fcn);
setColor(p,colorArray(1,i));
pointArray{i}=p;
getPosition(p)
end
When I start to set points on the image I get results like [675.000 538.000], which means that the x part of the coordinate is 675 and the y part is 538, right? This is what the MATLAB documentation says, but since the image is 576*120 (as displayed in the window) this is not logical.
It seemed to me like, somehow, getPosition returns the y coordinate first. I need some clarification on this.
Thanks for help
I just tried running your code in MATLAB 7.8.0 (R2009a) and had no problems with image sizes of either 576-by-120 or 120-by-576 (I was unsure which orientation you were using). If I left click inside the image, it places a new movable point. It did not allow me to place any points outside the image.
One small bug I found was that if you left-click in the image, then drag the mouse pointer outside the image while still holding the left button down, it will place the movable point outside the image and won't display it, displaying a set of coordinates that are not clipped to the axes rectangle.
I'm not sure of what could be your problem. Perhaps it's a bug with whatever MATLAB version you are using. I would suggest either restarting MATLAB, or clearing all variables from the workspace (except for the image data im).
Might be worth checking to see which renderer you are using (Painter or OpenGL), a colleague showed me some wierd behaviour with point picking when using the OpenGL renderer which went away when using the Painter renderer.
Your code uses the Image Processing Toolbox, which I don't have, so this is speculation. The coordinate system is probably set to the figure window (or maybe even the screen), not the image.
To test this, try clicking points outside the image to see if you can find the origin.