I currently have a vector field that looks something like this, generated with the following basic structure, where Z is some matrix:
[X,Y] = meshgrid(x,y)
[grad_x, grad_y] = gradient(Z)
quiver(X,Y,grad_x,grad_y)
I would like for this plot to be rescaled, such that the x-axis ranges from 1.5 to 3.8 and the y-axis ranges from 100 to 250, but for the arrows themselves to look identical. The only difference in the figure should be the axes labels.
I have tried:
grad_x_rescaled = [(grad_x - min(grad_x))./(max(grad_x)-min(grad_x))].*(3.8-1.5);
grad_y_rescaled = [(grad_y - min(grad_y))./(max(grad_y)-min(grad_y))].*(250-100);
But the problem with this is that although the grad_x and grad_y get rescaled overall, the scaling of the arrows themselves relative to each other are not conserved, and results in below (note the thick black streaks are presumably arrowheads, but the important thing is that the direction and relative sizes of the arrows are not exactly like in the first case.
Is there a matlab function or an expression to renormalize data into a new range, but such that the renormalized data is scaled relative to itself (such as the arrows should be scaled the same relative to one another)?
To simply change the axes tick labels you could use Matlab's ability to specify tick marks and tick labels. Basically you would just tell Matlab where to put the ticks and what the labels should say like this:
xticks(linspace(0,1,6))
xticklabels(linspace(1.5,3.8,6))
yticks(linspace(0,1,6))
yticklabels(linspace(100,250,6))
Related
I'm trying to create a 24x366 heatmap using imagesc with the x-axis labelled at 13 evenly spaced points as {'jan 15','feb 15',...,'dec 15','jan 16'}, and the y-axis labelled at every row from 1 to 24, like this:
Desired imagesc axes
When I run the script, it displays the y-axis as I want it, but it only displays the first label on the x axis and ignores the others. I can get this to work for a plot, but I can't get it to work for an imagesc. I've included my script below. Does anyone know how to make the imagesc display all 13 labels on the x-axis at evenly spaced intervals?
mylabels = {'jan 15','feb 15','mar 15','apr 15','may 15','jun 15','jul 15','aug 15','sep 15','oct 15','nov 15','dec 15','jan 16'};
testspacing = (1:(60*24*30):528480);
figure
imagesc(rand(24,366))
set(gca,'XTick',testspacing,'XTickLabel',mylabels,'XTickLabelRotation',45,'YTick',1:24,'YTickLabel',1:24)
The problem with your code is that your only one of your ticks from testspacing falls in the range of the plot testspacing=[1 43201 ...]. You can check the range of your x-axis by running xlim without any arguments.
You can rescale testspacing to fit your x-axis e.g. like:
xmax = 366;
mylabels = {'jan 15','feb 15','mar 15','apr 15','may 15','jun 15','jul 15','aug 15','sep 15','oct 15','nov 15','dec 15','jan 16'};
testspacing = (1:(60*24*30):528480);
testspacing = testspacing/max(testspacing)*xmax;
figure
imagesc(rand(24,xmax))
set(gca,'XTick',testspacing,'XTickLabel',mylabels,'XTickLabelRotation',45,'YTick',1:24,'YTickLabel',1:24)
or you just generate testspacing properly. Since you are putting own labels on the axis anyway you might just choose use testspacing = [0:30.5:366] or testspacing = [0:30:366] depending on what you want. This will also help you debug your own code later on.
On another note you should think about reducing the number of labels in general and decide which of the labels are really helpful. Maybe every 2nd or 3rd month is enough. You can "remove" individual labels by setting them to empty strings ''.
I am generating multiple plots of different datasets in succession using MATLAB. I would like the legend positions to be such that they don't overlap on the plotted lines and it would be ideal if this placement could be done automatically.
I am aware of setting the 'Location' to 'best' to achieve this but the placement of the legend tends to be awkward when 'best' is used (below). Also, I would like the legend to be inside the plot. I also came across a way to make the legend transparent (here) so that it does not render the plotted data invisible, but explicitly placing the legend elsewhere is what I am looking for.
Is there a way to place the legend at the extremes of the image ('NorthWest', 'SouthWest' etc) automatically such that it does not overlap on the plotted data (apart from the methods suggested above)?
So, you have tried using Location instead of Position? For example:
x =1:100;
y = x.^2;
lgd = legend('y = x.^2');
set(lgd,'Location','best')
and you are getting odd results correct? A quick way of solving this would be to still use Location, with best, and extract the coordinates:
lgd.Position
You should get something like this:
ans =
0.7734 0.3037 0.1082 0.0200
which maps to:
[left bottom width height]
You will need to focus on left and bottom. These two values, left and bottom, specify the distance from the lower left corner of the figure to the lower left corner of the legend, and they are analogous to the grid frame you are using.
Then, depending on the size of the frame (I would suggest you use axis([XMIN XMAX YMIN YMAX]) for this, if possible), you can pinpoint the position of the legend within the grid. What you can do next, is check if and which of your graphs in the plot cross paths with the legend (maybe define a relative distance function based on some distance threshold) and if they do, then randomly reposition the legend (i.e. change the values of left and bottom) and repeat until your conditions are met.
If this still troubles you I can write a short snippet. Finally, know that you can always opt for placing the legend on the outside:
set(lgd,'Location','BestOutside')
I have plotted a dot raster plot divided into various segments, which I would like to label. In my case, I have different attenuation values for the same frequency value and want to label the attenuation values in the y-axis.
It's a little unclear exactly what your trying to do but if you mean to label the entire axis using:
ylabel('sometext','fontsize',12);
If you mean to label specific ticks on the axis try using something like :
set(gca,'Ytick',[0:3],'YtickLabel',{'hello','world','foo','bar'});
Edit:
You would want to do something like this.
set(gca,'Ytick',[1:20:120],'YtickLabel',{'label1','label2','label3',etc...});
I am trying to plot x and y velocities using quiver function in MATLAB.
I have x,y,u and v arrays(with their usual meanings) with dimension 100x100
So, the result is my quiver plot is dense and I cannot see the arrows unless I zoom in.
Somewhat like this: quiver not drawing arrows just lots of blue, matlab
Take a look at my plot:
Is there any way to make quiver plot less dense(and with bigger arrows)? I am planning to clip x-axis range to 0-4. But anything apart from that?
I cannot make my mesh less dense for accuracy concerns. I am, however willing to ignore some fine data points if that's required to make the plot look better.
You can plot a reduced number of arrows by plotting, for example, (assuming your data are in arrays)
quiver(x(1:2:end,1:2:end),y(1:2:end,1:2:end),u(1:2:end,1:2:end),v(1:2:end,1:2:end))
where the 2 in this example means we plot only a quarter as many arrows. You can of course change it, as long as you change all of the 2's so that the arrays are all appropriately sized.
If you want to change the length of the arrows there are two options. Firstly, you can use the scale option scale=2 to scale the arrows by the amount specified, or you can normalise the velocities if you want to have all the arrows the same length. You do lose information doing that, because you can't compare the magnitude of the velocity by looking at the arrows, but it may be useful in some situations. You can do this by dividing u and v both by sqrt(u.^2+v.^2) (at the points you wish to plot arrows at.
Hope that helps and sets everything out nicely.
You need to make your interval value a bit larger in order to make your matrix more sparse.
This is very dense:
1:0.0001:100
This is very sparse:
1:1:100
EDIT:
If you have the Image Processing Toolkit you can use the imresize function to reduce the matrix resolution:
newMat = imresize(oldMat, newSize);
And if you don't have the Toolbox then you can resize in a similar manner to this example using interp2 Interpolation:
orgY = 1:size(oldMat,1);
orgX = 1:size(oldMat,2);
[orgX,orgY] = meshgrid(orgX ,orgY);
newY = linspace(1,size(mat,1),newHeight);
newX = linspace(1,size(mat,2),newWidth);
[newX,newY] = meshgrid(newX,newY);
newMat = interp2(orgX,orgY,mat,newX,newY);
And thanks to #David, if you want to just strip out some individual points you can simply do:
xPlot=x(1:2:end)
I want to display pretty dendrograms for some agglomerative clusters I am generating in Java. I write the clusters out to a file in Newick format. Then, I can get a pretty picture that is almost what I want.
tr = phytreeread('myfile.tree')
phytreetool(tr)
Unfortunately, the X axis is not what I want. I would prefer to "reverse" the axis, because the iterations of the clustering progress from right to left, e.g. firstName and setFirstName get clustered in the first iteration. Does anybody know how I can do that, or at least turn off the X axis labeling? (What is the default axis trying to tell me anyway?)
First, you will need to gain access to the handle for the axes in which the dendrogram is plotted. If it's the only figure open, you can use the function FINDALL like so:
phyAxes = findall(0,'Type','axes');
Now, what you want to change isn't the x-axis direction, since this will reverse the plotted dendrogram as well. You actually want to change just the labels used for the x-axis tick marks. If you want to just turn them off, you can do this:
set(phyAxes,'XTick',[]);
Now, I'm not sure what the x-axis is meant to tell you. In your example, it appears that each branch point is positioned at an integer value along the x-axis starting at 0 for the left-most branch point (the "root", I guess). The right-most branch containing firstName and setFirstName is positioned at a value of 21. If you want to change the axis labeling so that the right-most branch is at 0 and the left-most branch is at 21, you can modify the axes as follows:
set(phyAxes,'XTick',0:21,'XTickLabel',num2str((21:-1:0).'));
This could help you?
set(gca,'XDir','reverse')
EDIT
You may find a lot of interesting here. Cheers!
I needed something similar. I don't know if it is new to Matlab R2021b, but there is now a plot(tree) function which will draw the tree on a regular Matlab figure. After plotting, I identify the largest X value and update the XTickLabels.
B = [1 2 ; 3 4];
tree = phytree(B);
h = plot(tree);
ax = h.axes;
xdata = get(findobj(h.axes,'Type','Line'),'XData');
maxdist = max([xdata{:}]);
ax.XTickLabel = num2str(maxdist - str2double(ax.XTickLabel));
Phylogenetic tree with reversed Xtick labels