I am trying to get the y coordinates on a xy plot by clicking on the plot. This is very similar to the function ginput which will generate a cursor and by clicking on the plot you can get the x and y coordinates where the cursor is placed. However, for my particular purpose, I want to have a line cross the figure instead of cursor as a guide of determining the right y value to use. Is there any function in matlab can do this? If not, what is the way to do it? Any help is greatly appreciated.
I don't believe there is a pre-packaged function for that, but you can do it using the strategies described in this video tutorial from Doug Hull, with slight modifications.
Related
I am currently trying to use spectral-methods to analyse topographic landscapes.
When i FFT the landscape and plot the power-spectrum. From the power-spectrum an orientation of the structures in the landscape can be found.
2D power-spectrum:-
In this power-spectrum, i would like to make a cross-section.
This is easy when the peak amplitude orientation is along the x or y-axis.
But for this area (and others), this is not the case.
Cross-section from another area - orientated along the y-axis:-
My problem is i want to make a cross-section along the peaks in 1, and i just cant seem to figure it out how.
If anyone could point me towards some solution for this. Been stuck here for a couple of days now.
Edit 1
I would like the cross-section, to be a line along the peak orientation.
Edit 2
Improved the first image to show where i want my cross-section
My solution was, as GameOfThrows suggested:
Pick 2 (or more) points on the orientation i want
used Least squares on the points to create the line
Setup a meshgrid for the interpolation.
Use the interp2 function on the new line.
define a proper axis for the section
In my final cross section i ended up having multiple lines in it, that way i was sure to hit the max amplitudes.
i was a little with the answer to my question, but i have been busy :)
You can use ginput built-in matlab function to store 2 (x,y) coordinates of your power spectrum and then use this values to delimit a profile to be interpolated.
I am workin on a some sort of System test wherein i have a set of readings in the form of a .mat file.
It has a structure in the .mat file with one field as Measurement. It has several Arrays(e.g air mass flow, velocity, carbon content) which further have fields like time and value.
From these, I Need to plot the velocity and the air mass flow against time. For that i wrote the following command which gave me the corresponding plots:
plot(Measurement.(Measurement.air_mass_flow.time),Measurement.air_mass_flow.value)
plot(Measurement.(Measurement.velocity.time),Measurement.velocity.value)
Now i Need to create a script in matlab wherein i can get both the curves one under the other i.e. on the same page. Can anyone help in the Approach i should procede with ?
ok now i will further extend my question.
I have two fields as velocity and acceleration. I Need to plot it on the same curve with grids on for the comparison. But the y axis for both are different.
the velocity y-axis is: (0:20:120), which should be displayed on the left side and the acceleration y-axis is: (0:2:12) which should be displayed on the right side.
i wrote the following code for this:
plot(Measurement.(Measurement.VehV_v.time),Measurement.VehV_v.value)
grid on
set(gca,'xtick',[0:500:2000])
set(gca,'ytick',[0:20:120])
hold on
plot(Measurement.(Measurement.accel_w.time),Measurement.accel_w.value)
grid on
set(gca,'xtick',[0:500:2000])
set(gca,'ytick',[0:2:12])
Do i Need to write a function for that as i am directly reading the values from the structure.
plotyy() also doesnt seem to work
But the axis are not matching and the graph for acceleration is very small. Could anyone help me out with this ?
I also want to add a Picture of the Graphs here but unfortunately there is some error here. I hope the question is clear without the Picture.
Yes you can use the subplot command, e.g.:
figure
subplot(1,2,1)
plot(Measurement(Measurement.air_mass_flow.time),Measurement.air_mass_flow.value)
subplot(1,2,2)
plot(Measurement.(Measurement.velocity.time),Measurement.velocity.value)
You can use help subplot on Matlab for further details or have a look at this:
https://www.dartmouth.edu/~rc/classes/matlab_graphics/Matlab-subplots.html
For the function z= 10+pow((x-2),2)+pow((y+5),2), I want to represent in a 3D plot every value of z for each (x,y) pair , with a display delay before each new value of z (like a moving point).
The values for x,y are read from files.
I tried to modify Jacobs code from Creating a point moving along a graph in MATLAB, but I couldn't get it to work for my 2 variable function.
I would like a general solution, because I will also need this plotting for a N-variable function.
Have a look at the following question and see if it answers yours:
animate plot / trajectory in matlab / octave
I have a set of (X, Y) coordinates which, when plotted produce a graph as in the pictures below. What I am trying to do, is to find the coordinates of the areas (corner points) circled in red.
I have been trying to find ways to accomplish this, as those actual turning points represents my area of interest. Please note that I do not have the actual equation for those coordinates.
I would find it grateful if someone could please advise me, or give me some directions on how to go about this, either by using Matlab, or even some other ideas using some C++ tools.
I manage to solve this using a combinaison of the Point Cloud Library and Matlab. The former helped me to separate the coordinates in line segments (RANSAC) and using the latter, I was able to get the Equation of each line segments (Curve Fitting), and simply compute the intersection point through some basic math calculation.
I have a 2XN vector of points. I'd like to plot it and then enable the user to select one of the points by clicking on that point. I guess I can do it by myself by getting the mouse coordinates and select the point closest to them etc. I am wondering whether matlab provides a plug-and-play method for doing this?
There is no easy way to accomplish this, as far as I know.
You can do one of the following:
Check the distance and select the closest point (As you said yourself)
Call the plot command N times, and assign a different callback for each plot.
In this case you create the graphics in the following way:
for i=1:N
plot( X(i),Y(i), 'o', 'ButtonDownFcn', #(x)CallBack(x,i));
end
And the callbacks look like that:
function CallBack(x,i)
fprintf(1,'A callback on P[%d] was called');
end
If you want a special case of 2xN points: a draggable polygon, you can use the impoly command instead.