I am trying to plot both horizontal and vertical lines on a histogram that will be accurate to changing limits on both the x and y axes. I was using the line(X,Y) function, but cannot find a useful way to get the lines to be set depending on the parameters of the graph window.
I'm not entirely clear on what you want but here's the simplest answer to what I think you want:
Makes a sample histogram
y = randn(100,1);
hist(y,10)
Get the current limits of the x and y axes
xlimits = get(gca, 'XLim');
ylimits = get(gca, 'YLim');
Computes a single numeric value to plot a horizontal line.You'll want to replace this with your specific function of the axes limits
halfpt = ((ylimits(2)-ylimits(1))/2) + ylimits(1);
line(xlimits, [halfpt halfpt])
I'm not sure, but from your comment I'm suspecting that you aren't changing your axes programmatically, with say set(gca,'Xlim', [0 10]) but that you want to be able to drag the axes of your your figure with the mouse, say by using that hand/pointer button in the figure editor. In which case, one solution is to make your figure a GUI and write a callback function that handles line plotting that is a function of the xlim and ylim. Here's an example that always keeps the line in the middle of the axes regardless of how they are dragged:
function myGUI
figure('WindowButtonMotionFcn',#myCallback)
y = randn(100,1);
hist(y,10)
function myCallback(src,eventdata)
xlimits = get(gca, 'XLim');
ylimits = get(gca, 'YLim');
halfpt = ((ylimits(2)-ylimits(1))/2) + ylimits(1);
lh = findall(gcf,'Type','Line');
delete(lh);
myline = line(xlimits, [halfpt halfpt])
end
end
Related
Please see the following code which creates a 2 by 2 subplot with some plots:
x = linspace(0,2*pi);
y = sin(x);
hfig = figure('Position',[1317 474 760 729]);
subplot(2,2,1)
plot(x,y)
ylabel('plot1');
subplot(2,2,2)
plot(x,y.^2)
ylabel('plot2');
subplot(2,2,3)
plot(x,y.^3)
ylabel('plot3');
subplot(2,2,4)
plot(x,abs(y))
ylabel('plot4');
in each one, I have added labels by hand in Tools: Edit plot (a) (b) (c) (d) producing this figure:
The problem is, if I resize the plot they are no longer aligned with the ylabel text:
Is there a way to add these labels programmatically and have them automatically align to the ylabel text? I am surprised MATLAB does not have something like this built in already.
Thanks
This is not something that is easy to do without attaching a listener to the figure resize event (see example), and doing some computations related to aspect ratios.
It's not entirely clear what sort of objects your labels are (text or annotation), so I'll just show how to do this programmatically using the text command, which creates labels in axes coordinates (as opposed to figure coordinates). This doesn't solve the problem entirely, but it looks better, possibly to an acceptable degree:
function q56624258
x = linspace(0,2*pi);
y = sin(x);
hF = figure('Position',[-1500 174 760 729]);
%% Create plots
[hAx,hYL] = deal(gobjects(4,1));
for ind1 = 1:3
hAx(ind1) = subplot(2,2,ind1, 'Parent' , hF);
plot(hAx(ind1), x,y.^ind1);
hYL(ind1) = ylabel("plot" + ind1);
end
hAx(4) = subplot(2,2,4);
plot(hAx(4), x,abs(y));
hYL(4) = ylabel('plot4');
%% Add texts (in data coordinates; x-position is copied from the y-label)
for ind1 = 1:4
text(hAx(ind1), hYL(ind1).Position(1), 1.1, ['(' char('a'+ind1-1) ')'], ...
'HorizontalAlignment', 'center');
end
Note several modifications to your code:
The handles returned by some functions that create graphical elements are now stored (mainly: hAx, hYL).
All functions that create graphical elements (subplot, plot, ylabel) now have the target (i.e. parent or container) specified.
I changed the 'Position' of the figure so that it works in my setup (you might want to change it back).
figure;
ax1 = axes;
figure;
ax2 = axes;
x = 0; y = 0;
while ishandle(ax1) && ishandle(ax2)
x = x + 1;
y = y + 1;
figure(1)
scatter(x,y, 'MarkerEdgeColor', 'red')
hold on
figure(2)
scatter(x,y, 'MarkerEdgeColor', 'blue')
hold on
end
In my script I have multiple figures, which are going to be updated in a loop. The figures have to be displayed, while the script is running. Unfortunately the currently updated figure is always popping in the foreground, which makes it impossible to monitor a certain figure. I understand that the calling of figure(1) and figure(2) causes this behaviour, but I how can I plot to these figures, without bringing the window into foreground?
As mikkola suggested in a comment, you can specify to which axes scatter or plot add data points. However, there is a better method: create a single line object, and update its xdata and ydata properties. This is both faster and more memory efficient. Your code would become:
x = 0; y = 0;
figure;
h1 = plot(x,y,'ro');
figure;
h2 = plot(x,y,'bo');
while ishandle(h1) && ishandle(h2)
x = x + 1;
y = y + 1;
h1.XData(end+1) = x;
h1.YData(end+1) = y;
h2.XData(end+1) = x;
h2.YData(end+1) = y;
drawnow
pause(0.1)
end
I keep a set of rules of thumb for when working with MATLAB handle graphics. These are relevant to this question:
Use figure only to create a new figure, or to bring an existing figure to the front (which you want to avoid in general, but sometimes is necessary).
Always specify with which figure or axes you want to work, by keeping and using their handles. I never rely on gcf or gca (not explicitly nor implicitly). Using the current figure is useful when typing on the command line, but in a script or a function there is the real danger than someone clicks randomly on windows while the function is executing. Creating a window then writing to gcf could end up writing to a different figure (really, I click on random things all the time).
Don't create more objects than necessary. Creating a new line object for every point you plot is wasteful.
Note also that plot(...'o') is equivalent to scatter(...) unless you specify a different color or size for each point. But using the dot size or color to specify additional information is not a good way to convey that information. Read Tufte's "The visual display of quantitative information" if you're interested in learning about effective communication through graphs.
The relevant part can be found in the part of the documentation of scatter that includes the input ax:
scatter(ax,___) plots into the axes specified by ax instead of into
the current axes.
This allows the user to specify an axis handle pointing to which axes should be used for drawing the scatter plot. Thus if you skip using figure in your code and use the ax input instead, you avoid the "bring to front" behavior associated with figure.
You can modify your code as follows:
figure;
ax1 = axes;
figure;
ax2 = axes;
x = 0; y = 0;
while ishandle(ax1) && ishandle(ax2)
x = x + 1;
y = y + 1;
scatter(ax1, x,y, 'MarkerEdgeColor', 'red')
hold on
scatter(ax2, x,y, 'MarkerEdgeColor', 'blue')
hold on
end
I have written the following code to try and retrieve ONLY the axes and its plot from my MATLAB GUI.
F = getframe(gca);
figure();
image(F.cdata);
saveas(gcf,'PlotPic','png');
close(gcf);
I noticed, however, that this method does not include ANY of my axis labels or title. Is there any way which I can get the getframe function to include the axis labels and title?
I tried the following code but it did exactly the same
pl = plot(x,y);
xlabel('x')
ylabel('y')
ftmp = figure;
atmp = axes;
copyobj(pl,atmp);
saveas(ftmp,'PlotPic.png');
delete(ftmp);
I would do it using the rect option of the getframe function.
Basically you can provide a 2nd input argument to getframe, which then captures the content of the rectangle specified as argument. The nice thing is that you can use the handles to an axes, so it does not capture your whole GUI figure but rather a specific axes.
For example, using this line:
F = getframe(gca,RectanglePosition);
Concretely, you could set the coordinates of the rectangle such that they span both axis labels and the title as well. Here is a sample code. The pushbutton callback executes getframe and opens a new figure with the content of F.cdata:
function GUI_GetFrame
clc
clear
close all
%// Create GUI components
hFigure = figure('Position',[100 100 500 500],'Units','Pixels');
handles.axes1 = axes('Units','Pixels','Position',[60,90,400,300]);
handles.Button = uicontrol('Style','Push','Position',[200 470 60 20],'String','Get frame','Callback',#(s,e) GetFrameCallback);
%// Just create a dummy plot to illustrate
handles.Period = 2*pi;
handles.Frequency = 1/handles.Period;
handles.x = 0:pi/10:2*pi;
handles.y = rand(1)*sin(handles.Period.*handles.x);
plot(handles.x,handles.y,'Parent',handles.axes1)
title('This is a nice title','FontSize',18);
guidata(hFigure,handles); %// Save handles structure of GUI.
function GetFrameCallback(~,~)
handles = guidata(hFigure);
%// Get the position of the axes you are interested in. The 3rd and
%// 4th coordinates are useful (width and height).
AxesPos = get(handles.axes1,'Position');
%// Call getframe with a custom rectangle size.You might need to change this.
F = getframe(gca,[-30 -30 AxesPos(3)+50 AxesPos(4)+80]);
%// Just to display the result
figure()
imshow(F.cdata)
end
end
The GUI looks like this:
And once I press the pushbutton, this is the figure that pops up:
So the only trouble you have is to figure out the dimensions of the rectangle you need to select to capture the axis labels and the title.
Hope that solves your problem!
I'm trying to position MATLAB's ticks to line up with my grid, but I can't find a good way to offset the labels.
Also, if I run set(gca,'XTickLabel',1:10), my x tick labels end up ranging from 1 to 5. What gives?
You need to move the ticks, but get the labels before and write them back after moving:
f = figure(1)
X = randi(10,10,10);
surf(X)
view(0,90)
ax = gca;
XTick = get(ax, 'XTick')
XTickLabel = get(ax, 'XTickLabel')
set(ax,'XTick',XTick+0.5)
set(ax,'XTickLabel',XTickLabel)
YTick = get(ax, 'YTick')
YTickLabel = get(ax, 'YTickLabel')
set(ax,'YTick',YTick+0.5)
set(ax,'YTickLabel',YTickLabel)
Or if you know everything before, do it manually from the beginning:
[N,M] = size(X)
set(ax,'XTick',0.5+1:N)
set(ax,'XTickLabel',1:N)
set(ax,'YTick',0.5+1:M)
set(ax,'YTickLabel',1:M)
The marked answer works with a surf or mesh plot, however, I needed a solution which worked for a 2d plot.
This can be done by creating two axes, one to display the grid and the other to display the labels as follows
xlabels=1:1:10; %define where we want to see the labels
xgrid=0.5:1:10.5; %define where we want to see the grid
plot(xlabels,xlabels.^2); %plot a parabola as an example
set(gca,'xlim',[min(xgrid) max(xgrid)]); %set axis limits so we can see all the grid lines
set(gca,'XTickLabel',xlabels); %print the labels on this axis
axis2=copyobj(gca,gcf); %make an identical copy of the current axis and add it to the current figure
set(axis2,'Color','none'); %make the new axis transparent so we can see the plot
set(axis2,'xtick',xgrid,'XTickLabel',''); %set the tick marks to the grid, turning off labels
grid(axis2,'on'); %turn on the grid
This script displays the following figure :
I am looking for a way to overlay an x-y time series, say created with 'plot', on top of a display generated by 'contourf', with different scaling on the y-axes.
It seems that the typical way to do this in the case of two x-y plots is to use the built-in function 'plotyy', which can even be driven by functions other than 'plot' (such as 'loglog') as long as the input arguments remain the same (x,y). However, since in my case contourf requires three input arguments, 'plotyy' seems to not be applicable. Here is some sample code describing what I would like to do:
x1 = 1:1:50;
y1 = 1:1:10;
temp_data = rand(10,50);
y2 = rand(50,1)*20;
figure; hold on;
contourf(x1,y1,temp_data);
colormap('gray');
plot(x1,y2,'r-');
Ideally, I would like the timeseries (x1,y2) to have its own y-axes displayed on the right, and be scaled to the same vertical extent as the contourf plot.
Thanks for your time.
I don't think there's a "clean" way to do this, but you can fake it by overlaying two axes over each other.
x1 = 1:1:50;
y1 = 1:1:10;
temp_data = rand(10,50);
y2 = rand(50,1)*20;
figure;
contourf(x1, y1, temp_data);
colormap('gray');
h_ax = gca;
h_ax_line = axes('position', get(h_ax, 'position')); % Create a new axes in the same position as the first one, overlaid on top
plot(x1,y2,'r-');
set(h_ax_line, 'YAxisLocation', 'right', 'xlim', get(h_ax, 'xlim'), 'color', 'none'); % Put the new axes' y labels on the right, set the x limits the same as the original axes', and make the background transparent
ylabel(h_ax, 'Contour y-values');
ylabel(h_ax_line, 'Line y-values');
In fact, this "plot overlay" is almost definitely what the plotyy function does internally.
Here's example output (I increased the font size for legibility):