Reorganizing a large matrix into 4 other matrixes

I am trying to write a code that will produce a contour plot of many PIV Data points from DaVis .txt files.

The .txt file has 4 columns of data (X coordinates, Y coordinates, U velocity, V velocity). As of now I have the code reading this file with dlmread skipping the first row. I need the program to reorganize the X column into its own matrix of 173x124, and the other columns to do the same for their own matrixes of the same size. I have the X,Y,U,V matrixes set to empty matrixes that need to be filled.

type B00001.txt;
A=dlmread('B00001.txt', '',1,0);

X=zeros(173,124);
Y=zeros(173,124);
U=zeros(173,124);
V=zeros(173,124);

pcolor(X,Y,U); 
hold on
shading interp
colormap(jet);
colorbar

[Sriram Tadavarty]

Ryan, can you place the B00001.txt file with the paperclip icon here?

What is the dimension of X column? Is that of value exactly equal to 173 x 124.

If yes, you can use reshape function. Like,

X = reshape(data(:,1),173,124);

Y = reshape(data(:,2),173,124);

U = reshape(data(:,3),173,124);

V = reshape(data(:,4),173,124);

Hope this helps.

Answer 1

[Sriram Tadavarty]

Hi Ryan,

Thanks for attaching the code.

The data is present in a matrix form with four columns covering X, Y, U, and V. You can just use the code that is placed in the comments and it will work.

Placing here again:

type B00001.txt;
A=dlmread('B00001.txt', '',1,0);

X = reshape(A(:,1),173,124);
Y = reshape(A(:,2),173,124);
U = reshape(A(:,3),173,124);
V = reshape(A(:,4),173,124);

pcolor(X,Y,U); 
hold on
shading interp
colormap(jet);
colorbar

Hope this helps.

Regards,

Sriram

[rwn]

Thank you very much!