I have 2 sets of data I want to plot on the same graph.
First an histogram:
hist(data1);
ax1 = gca;
I set the next set of axis, y on the other side
ax2 = axes('Position',get(ax1,'Position'),...
'XAxisLocation','bottom',...
'YAxisLocation','right',...
'Color','none',...
'XColor','k');
If I use line() to plot my data it works:
line(data2a, data2b, 'Color', 'r', 'LineStyle', '-', 'Marker', '.', 'Parent', ax2);
But if I use plot(), the histogram is erased and both axis appear on the left.
plot(ax2, data2a, data2b);
Can somebody figure out why the second axis is not valid for plot()?
You should check out doc hold.
Axes in MATLAB have the 'NextPlot' property, specifying what to do when a new plot-function is issued on this axis.
The default for 'nextplot' is replace, meaning that before anything new is drawn, existing plots are erased.
Using hold(ax, 'on') or set(ax, 'nextplot', 'add') you can specify that new plots are added to the existing ones, instead of replacing them.
The reason that line and plot behave differently is, that high level functions (like plot) respect this axis property, while low-level functions like line, patch and others do not. They are added to axis in any case and do not remove existing children.
EDIT:
Now I'm noticing that ax2 should be empty in your case - maybe just try the above nevertheless ;)
Related
I have a figure as shown here, with each color indicating the value of a third variable. I attempted to create a colorbar with the corresponding colors and values. For this purpose first I get the Color of the 'Children' of the axes as follows:
curves = get(gca, 'Children');
mycolorset = cat(1, curves(:).Color);
Then I realized that the order of the colors (same as the order of the Children) is reversed compared to the order of plotting. So I had to apply flipud to the colors to make the correct colormap:
set(gcf, 'Colormap', flipud(mycolorset));
Interesting fact is that Plot Browser shows the curves in the correct order.
Now I want to know, is this a universal feature of all Children in Matlab to be reversed? Do you know a case that this becomes useful at all?
The Children of an axes are ordered such that the children near the beginning are displayed on top of children near the end of the list of children (if the SortMethod is set to 'childorder' or if you have just a 2D plot).
If you're dynamically adding multiple 2D plots to an axes, the default behavior of MATLAB is to place new plot objects on top of old plot objects, therefore they need to be appended to the beginning of the Children list.
figure;
hold on
plot1 = plot(1:10, 'LineWidth', 10, 'DisplayName', 'plot1');
plot2 = plot(10:-1:1, 'LineWidth', 10, 'DisplayName', 'plot2');
legend([plot1, plot2])
get(gca, 'Children')
% 2x1 Line array:
%
% Line (plot2)
% Line (plot1)
If you want to alter which plot is displayed on top of which, you can modify the ordering of the Children or you can just use the handy uistack command to do this for you.
set(gca, 'Children', flipud(get(gca, 'Children'))) % Or uistack(plot1, 'top')
get(gca, 'Children')
% 2x1 Line array:
%
% Line (plot1)
% Line (plot2)
This stacking behavior isn't just limited to plot objects in axes. You can alter the Children ordering on most UI elements (including uipanels, figures, etc.) to determine the visual stacking of the elements.
I use plotyy to put two plots in one graph:
f = figure('Color','white');
[ax,p1,p2] = plotyy(xx, yy1, xx, yy2);
ylabel(ax(1),'Phase','FontSize',18);
ylabel(ax(2),'Spectrum','FontSize',18);
set(ax,{'ycolor'},{'k';'k'});
set(p1,'LineWidth',2,'Color',[0.4940,0.1840,0.5560]);
set(p2,'LineWidth',2,'Color','red');
xlabel(ax(1),['Frequency [THz]'],'FontSize',18);
set(ax,'FontSize',14)
Figure is displayed perfectly, but when I try to save it as fig something like misaligned boxes appears.
I tried to use linkaxes, but with no result.
plotyy has been one of my favorite MATLAB functions to love to hate. It's a really useful function that I always seem to run into bugs with, to the point where I've completely stopped using it in favor of just stacking two (or more) axes objects and plotting to them separately. You can then set the Position property of the 'sub' axes to the same as your primary axes and they will stack nicely.
A functional example:
xx = linspace(-15,15,100);
yy1 = sin(xx);
yy2 = cos(xx);
f = figure('Color','white');
ax(1) = axes('Parent', f);
ax(2) = axes('Parent', f, 'Color', 'none', 'XTick', [], 'YAxisLocation', 'right');
p1 = plot(ax(1), xx, yy1);
hold(ax(2), 'on'); % Hold to preserve our axes properties set above
p2 = plot(ax(2), xx, yy2);
hold(ax(2), 'off');
ylabel(ax(1),'Phase','FontSize',18);
ylabel(ax(2),'Spectrum','FontSize',18);
set(ax,{'ycolor'},{'k';'k'});
set(p1,'LineWidth',2,'Color',[0.4940,0.1840,0.5560]);
set(p2,'LineWidth',2,'Color','red');
xlabel(ax(1),'Frequency [THz]','FontSize',18);
set(ax,'FontSize',14)
set(ax, 'ActivePositionProperty', 'position'); % Resize based on position rather than outerposition
set(ax(2), 'Position', get(ax(1), 'Position')); % Set last to account for any annotation changes
Along with stacking the axes you will also note that I have set the ActivePositionProperty to position (rather than outerposition). MATLAB resizes axes automatically when the Units property is set to Normalized, and it seems like this is the main spot where the issue is arising. On resizing, MATLAB also modifies the OuterPosition value for the second axes, causing it to resize the plot portion. The difference is small, [0 0 1 1] vs. [0 0.0371 1.0000 0.9599] in my case, but the effect is obviously very pronounced. You can use get and set to fix this, but you'll have to do it on every resize which is fairly annoying. The alternative is to resize based on the Position, which seems to alleviate the issue and is a tweak present in the R2015b implementation of plotyy. This also fixes plotyy except for cases where the window is very small, so I have left my answer with the more generic approach.
Please, create two functions to be able to reproduce what I mean:
First function:
function testPlot1()
pointData = rand(20000,3);
figure;
%hold on; % <- if commented out, does not work
plot3(pointData(:,1), pointData(:,2), pointData(:,3),'Marker', '.', 'MarkerEdgeColor', 'b','MarkerSize', 5, 'LineStyle', 'none');
axis equal;
xh = xlabel('X');
yh = ylabel('Y');
zh = zlabel('Z');
set([xh,yh, zh],...
'fontweight','bold',...
'fontsize',14,...
'color',[0,0,0]);
view(0,20);
end
Second function:
function testPlot2(fighandle)
axes(fighandle);
hold on;
plot3([0 3],[0 3],[0 3], 'r', 'LineWidth', 10);
end
If you now call
testPlot1();testPlot2(gca)
you will get the following:
If you however uncomment the "hold on" line in testPlot1() and call the above statement again, you will get:
To me this is unclear behavior. In the first case, testPlot1() creates a figure, draws the point cloud into it and modifies the axes properties. Then the call to testPlot2(gca) adds the line to the figure, but the line is clipped.
In the second case however the line is not clipped anymore. Why is it now not clipped and previously it was?
It seems to be related to the changes I make in the axes properties in testPlot1(). Could somebody explain this behavior to me? (why does it work with hold on, what do my changes in the axes properties cause)
hold on is a Matlab command (hold off turns it off again), where you can draw multiple elements on a single figure without the previous elements being erased.
What happens
If you call the plot function, a figure is created (or an already exisiting figure is used!) and Matlab draws a new plot into that figure. The previous plot that was in that figure is gone.
If you want to add more points to your plot, you can call hold on and then call plot again, this time with different numbers and maybe a different colour or so.
However, if you forget to turn hold off again for the active figure, any drawing activity you do (like plot) will be added to the figure. This is what happens in your second image in your question. You drew some points in the range 0 to 1, and then in the second function, you add some more but in the range 2 to 3. As a result, the axes expand to the range of 0 to 3.
Alternatively, you can call figure, which will cause a new figure to appear. figure_handle = figure(); will return a figure handle, which you can pass to your function, in case you have multiple figures and want to change one of them after a while.
When the graph below is plotted, NSS1 which is simply a constant set equal to one is right on the top border of the graph and thus hard to see.
How can I change the length of the y-axis to say 1.2 so that the NSS1 can be seen more clearly?
lambda=5;
tau=0:30;
tau(1)=0.000001;
NSS1=1*ones(1,31);
NSS2=(1-exp(-tau/lambda))./(tau/lambda);
NSS3=((1-exp(-tau/lambda))./(tau/lambda)-exp(-tau/lambda));
%ylim([0, 1.2])
plot(tau,NSS1,'-k*',tau,NSS2,'-k+',tau,NSS3,'-ko');
xlabel('t = 0 to 30y', 'FontSize',30)
ylabel('yield','FontSize',30)
The reason why ylim doesn't work if you put it before the plot command is that there is no axes object it can relate to.
So there are two options:
First, you create an axes object and hold it with hold on, so the upcoming plot is plotted on the same axis.
ax = axes; hold on;
ylim([0, 1.2])
plot(tau,NSS1,'-k*',tau,NSS2,'-k+',tau,NSS3,'-ko');
or second, you plot first, the command automatically generates an axes object and you can modify its y-limits afterwards:
plot(tau,NSS1,'-k*',tau,NSS2,'-k+',tau,NSS3,'-ko');
ylim([0, 1.2])
I am creating a GUI in Matlab. I have several axes in which I plot different graphs. I have set in some of the axes the property XTick to []. However, each time I plot a new graph in the same axes, the xticks appear again. I know I can delete them by using set:
set(handles.axes_0, 'XTick', []);
However, this creates a "flickering" effect: you see the ticks appearing and then dissapearing each time I plot something new.
Do you know how could I have an axes with the XTick disabled avoiding the flickering effect?
Some basic code:
figure(1); %create new figure
set(gca, 'XTick', []); %Disable xtick
plot([1 2 ], [2, 3]); %Plot something. Xtick appears again
set(gca, 'XTick', []); %Disable xtick until next plot
As Shai pointed out in a comment, when using hold on the ticks don't reappear. As I want to clean the previous plot before drawing the new one, I search for its identifier using findobj and then delete it. Finally, I draw the new plot with hold on. Example (suppose the axes handle is called handles.axes_0):
h = findobj(handles.axes_0,'Type','line');
if ~isempty(h)
delete(h);
end
hold on
plot(handles.axes_0,x,y);
hold off