I'm the MatLab newbie and I need some help to create a linear and non-linear axis in one chart.
I need to make chart with 2 different X-axes. One X-axis displays 1000/T at the bottom and the second X-axis displays a T at the top of the chart.
Example figure:
Do you have any idea how to solve this problem in MatLab?
Thanks.
This can be done by simply creating a second axes object at the same place as the first. Let's first create some data:
x1 = 1:0.1:3.5;
x2 = 1./x1;
y = (0.5*(x1-2)).^3;
Now we can create a normal plot with the first axes, and get the axes handle:
plot(x1,y,'-r');
ax(1) = gca;
Then we create the second axes object, at the same position as the first, and make the color none so it is transparent and the plot from below is still visible. As this adds a second Y axis too, we simply remove the Y ticks of the second axis.
ax(2) = axes('Position',ax(1).Position,'XAxisLocation','top','Color','none');
set(ax(2),'YTick',[]);
Now lets just format the second X axis as we like. Let's set the limits to the minimum and maximum of the x2 vector, and make it logarithmic:
set(ax(2),'XLim',[min(x2),max(x2)]);
set(ax(2),'XScale','log');
Now we still have the problem that the XTicks of ax(1) are also displayed at the top, and the XTicks of ax(2) are displayed at the bottom. This can be fixed by removing the box around the existing axes and creating a third axis without any ticks but with a box.
box(ax(1),'off');
box(ax(2),'off');
ax(3) = axes('Position',ax(1).Position,'XTick',[],'YTick',[],'Box','on','Color','none');
Now finally we can link the axes to be able to zoom correctly
linkaxes(ax);
And that should be it...
There is documentation for having a graph with two y-axes on the Mathworks website . .
http://de.mathworks.com/help/matlab/creating_plots/plotting-with-two-y-axes.html
It should be trivial to covert the concepts to the x-axis.
Related
I am trying to create a plot of failure strength vs material stiffness. However, the stiffness can be given as either [Pascal] or [Shore A] - I would like to use both in a double axis plot.
I've tried using plotyy but it will not allow me to have one line plot, nor does it allow the non-linear relation between Pascal and Shore A. I would like to plot one of them and then manually add the spacing between the others ticks.
Preferably I would like the stiffness on the x-axis, but y-axis can do if it is easier.
Any help is most welcome!
Example picture of what I'm trying to do
This may help you when you need double x-axes and double y-axes plot, but if you need single y-axes and two x-axes you can modify accordingly:
This example shows how to create a graph using the bottom and left sides of the axes for the first plot, and the top and right sides of the axes for the second plot.
Create the data to plot.
x1 = 0:0.1:40;
y1 = 4.*cos(x1)./(x1+2);
x2 = 1:0.2:20;
y2 = x2.^2./x2.^3;
Use the line function to plot y1 versus x1 using a red line. Set the color for the x-axis and y-axis to red.
Note: Starting in R2014b, you can use dot notation to set properties. If you are using an earlier release, use the set function instead, such as set(ax1,'XColor','r').
figure
line(x1,y1,'Color','r')
ax1 = gca; % current axes
ax1.XColor = 'r';
ax1.YColor = 'r';
Create a second axes in the same location as the first axes by setting the position of the second axes equal to the position of the first axes. Specify the location of the x-axis as the top of the graph and the y-axis as the right side of the graph. Set the axes Color to 'none' so that the first axes is visible underneath the second axes.
ax1_pos = ax1.Position; % position of first axes
ax2 = axes('Position',ax1_pos,...
'XAxisLocation','top',...
'YAxisLocation','right',...
'Color','none');
Use the line function to plot y2 versus x2 on the second axes. Set the line color to black so that it matches the color of the corresponding x-axis and y-axis.
line(x2,y2,'Parent',ax2,'Color','k')
The graph contains two lines that correspond to different axes. The red line corresponds to the red axes. The black line corresponds to the black axes.
Source:
http://www.mathworks.com/help/matlab/creating_plots/graph-with-multiple-x-axes-and-y-axes.html
Quick version
How can I control the x- and y-values for a 3-d bar plot in Matlab?
Details
Say we have an 10 x 20 data matrix and we plot it using bar3, and we want to set the x- and y-values. For instance:
foodat = rand(10,20);
xVals = [5:14];
yVals = [-3:16];
bar3(xVals, foodat);
xlabel('x'); ylabel('y');
Is there a way to feed it the yVals as well? Otherwise the y axes always defaults to [1:N].
Note I don't just want to change the labels using XTickLabel and YTickLabel. I need to change the actual values on the axes, because I am plotting multiple things in the same figure. It isn't enough to just change how the (wrong) axis ticks are labeled. So this is different from issues like this:
How can I adjust 3-D bar grouping and y-axis labeling in MATLAB?
Other things I have tried
When I try changing the xvals with:
set(gca,'XTick', xVals)
set(gca,'YTick', yVals)
The values are taken in, but actually show up on the wrong axes, so it seems x and y axes are switched using bar3. Plus, it is too late anyway as the bar graph was already plotted with the wrong x- and y-values, so we would end up giving ticks to empty values.
Note added
Matlab tech support just emailed me to let me know about the user contributed function scatterbar3, which does what I want, in a different way than the accepted answer:
http://www.mathworks.com/matlabcentral/fileexchange/1420-scatterbar3
I found a way of doing it. Ill give you a piece of code, then you'll need to "tidy up" , mainly the axis limits and the Xticks, as bar3 does set up the Xticks inside, so if you want others you'll need to set them manually yourself.
So the trick here is to get the Xdata from the bar3 handle. The thing here is that it seems that there is a handle for each row of the data, so you need to iterate for each of them. Here is the code with the current output:
foodat = rand(20,10);
xVals = [5:14];
yVals = [-3:16];
% The values of Y are OK if called like this.
subplot(121)
bar3(yVals, foodat);
subplot(122)
h=bar3(yVals, foodat);
Xdat=get(h,'XData');
axis tight
% Widdth of barplots is 0.8
for ii=1:length(Xdat)
Xdat{ii}=Xdat{ii}+(min(xVals(:))-1)*ones(size(Xdat{ii}));
set(h(ii),'XData',Xdat{ii});
end
axis([(min(xVals(:))-0.5) (max(xVals(:))+0.5) min(yVals(:))-0.5, max(yVals(:))+0.5])
Note: Y looks different but is not.
As you can see now the X values are the ones you wanted. If you'd want other size than 1 for the intervals between them you'd need to change the code, but you can guess how probably!
I have plotted a figure with multiple lines on it, and I have noticed that the lines for the plot overlap the x-axis when they are zero. Is there a way that I can essentially get the x-axis to plot on the top, rather than the lines?
Here is a MWE that does the same thing (I haven't put my exact code up as my dataset is quite big).
xdata=1:1:10;
ydata=[1;0.8;0.6;0.4;0.2;0;0;0;0;0];
line(xdata,ydata)
After I plot the lines (multiple per plot in my case), I do various other things with the axes so I get what I need (including adding a secondary set of axes). None of this seems to make any difference as to whether the x-axis is plotted on top of the lines or not.
I did have a search online but couldn't find anything to do with this.
The answer given by Luis is a nice workaround, but the official way to solve this problem is to use the layer property of the axis object, see the manual. To plot the axis on top of the data you do
set(gca,'Layer','top')
To automatically do this for all your plots, you can put the following line in your startup.m:
set(0,'DefaultAxesLayer','top')
This kind of answers you do not make up yourself, I only discovered this trick after asking more or less the same question on comp.soft-sys.matlab many years ago. See also this SO question.
After having plotted all your lines, plot a line on the x axis with the same color as the axis:
hold on
a = axis; %// gives xmin xmax ymin ymax
cx = get(gca,'Xcolor'); %// color of x axis
plot([a(1) a(2)], [a(3) a(3)], 'color', cx)
If the lines also overlap with the y axis and you also want that axis to appear on top, add the following:
cy = get(gca,'Ycolor'); %// color of y axis
plot([a(1) a(1)], [a(3) a(4)], 'color', cy)
I am using plotyy to plot two vectors on different y-axes. I wish to add a third vector to one of the two axes. Can someone please tell me why the following code is not working?
[ax h1 h2] = plotyy(1:10,10*rand(1,10),1:10,rand(1,10));
hold on; plot(ax(2),1:10,rand(1,10));
??? Error using ==> plot
Parent destroyed during line creation
I simply wish to add an additional vector to one of the axes (ax(1),ax(2)) created by plotyy.
Apply hold to the axis of interest.
[ax h1 h2] = plotyy(1:10,10*rand(1,10),1:10,rand(1,10));
hold(ax(2), 'on');
plot(ax(2),1:10,rand(1,10));
plotyy works by creating two axes, one on top of the other. You are carefully adding the new vector to the second axis. The hold property is also a per-axis property, so you just need to make sure that the hold is set on the same axis.
I would like to edit the axes in my series of images being displayed.
This is what my image looks like:
As you can see, it ranges from 0 to about 500 from top to bottom. Can I invert that?
Plus, I want to mirror the image being shown, so that it starts from left to right... or, if it's possible, to let the axes show from right to left.
To reverse an axis, you can set the 'XDir' or 'YDir' property of the current axes to 'reverse':
set(gca,'XDir','reverse'); %# This flips the x axis
Keep in mind that flipping an axis in this way flips everything in the plot as well. This probably isn't what you want to do for the y axis. You probably just want to flip the y axis labels, which you can do by modifying the 'YTickLabel' property in the following way:
yLimits = get(gca,'YLim'); %# Get the y axis limits
yTicks = yLimits(2)-get(gca,'YTick'); %# Get the y axis tick values and
%# subtract them from the upper limit
set(gca,'YTickLabel',num2str(yTicks.')); %'# Convert the tick values to strings
%# and update the y axis labels
Im = imread('onion.png');
Im = flipdim(Im ,1); % vertical flip the image.
axis xy; %set the xy to be at (0,0), this flips the image back again.
And whoop dee doo the image now have an y axis with the range from bottom to top!
How can I reverse the y-axis when I use the IMAGE or IMAGESC function to display an image in MATLAB? Another solution from mathworks
I found gnovice's answer helpful but it needed some tweaks for me. I think the following is a more general way to reverse the labels on the y axis. Simply sort the y tick numbers in descending order and relabel.
yTicks = get(gca,'YTick');
yTicks_reverse = sort(yTicks,2,'descend');
set(gca,'YTickLabel',num2str(yTicks_reverse.'));
I was redirected here from a duplicate question:
Flipping axis ticks
What 'ale' wanted to do there was just to flip the y-axis direction to be top down. If that is the only thing needed and nothing else, I would use:
axis ij