Plotting selective grid data

Respected Madam/ Sir,

I am trying to understand the interaction between 5 different stresses for certain material, of which 2 (tau13 and sigma33) I have held constant and the other three (sigma22, tau12, and tau23), I am varying with "meshgrid". However, I want to plot these 3 stresses based on a certain condition (iff_phi ==1), which needs to be checked at different values of phi. For a certain value of phi, if iff_phi == 1 is satisfied, then I need to plot these stresses/ save these stresses, delete the points in meshgrid for the sigma22, tau12, and tau23 then go to next value of phi. After checking for all values for phi, I need one isosurface and then head on to the next set of tau13 and sigma33 and carry on the same operation for all the values of sigma22, tau12, and tau23. I have written the attached code, however, unable to find a solution to save, plot and delete selective data from meshgrid.

Any sort of help is deeply solicited.

Sincerely,

Prathamesh Khorgade.

Answer 1

[Gojo]

Hi Prathamesh,

It seems that you are trying to plot the stresses based on condition “iff_phi==1”. You want to save those plots and delete the corresponding points from the meshgrid. By “delete the points in meshgrid” phrase, I am assuming that you do not intend to use the same points that resulted in “iff_phi==1” condition for further analysis.

You can use the provided condition to create a logical array. The array can then be used as indices for extracting relevant data points and plotting them.

For example, refer to the following code snippet:

condition = iff_phi==1;
scatter3(sigma2Grid(condition),t12Grid(condition),t23Grid(condition), 'filled'); 

You can also change the condition to check if “iff_phi” is approximately equal to 1 by introducing a threshold:

threshold = 0.1;         
condition = abs(iff_phi - 1) < threshold; 

After creating the plot, you can save the data in a “*.mat“ format, or export the 3D figure by referring to the following MATLAB Answer: https://www.mathworks.com/matlabcentral/answers/473586-is-there-a-way-to-export-save-a-matlab-3d-figure-so-that-a-3rd-party-can-view-it-with-the-rotation-e

As for “deleting” the data points in the meshgrid, you can assign them “NaN” values to prevent them from further consideration. For example, you can modify “sigma2Grid” as:

sigma2Grid(condition) = NaN; 

You can further use logical indexing to store the data points that fulfilled the mentioned condition for creating the “isosurface” plot.

I hope this helps!