How to surface or mesh plot imported data?

Hi!

I am new to matlab and could not find answer to how to import data organised like a matrix with a space as delimiter. It looks like this

x1 y1 z11

x1 y2 z12

x1 y3 z13 .... (etc)

until the last row

xn y1 zn1

xn y2 zn2

...

xn yn znn

I would like to have the x and y coordinates in the plane and the z coordinates as the height above the plane, either in a surf or a mesh plot, but all tutorials and help articles I find are for excel or use code that throws errors when I try to use them.

All help is appreciated! Thanks! :-)

Answer 1

[Star Strider]

‘... I need some commands that instructs MatLab that VarName1 and VarName2 are x and y respectively, while VarName3 is the z-coordinate.’

Perhaps something like this —

testout = readtable('YourExcelFile.xlsx')

testout.Properties.VariableNames = {'x','y','z'};

X = reshape(testout.x, 21,[]);

Y = reshape(testout.y, 21,[]);

Z = reshape(testout.z, 21,[]);

figure

plot(X, Y, Z)

xlabel('X')

ylabel('Y)

zlabel('Z')

Make appropriate changes to work with your file and data.

.

[Daniel Bozi]

Wow that really helped, thank you! Especially the readtable command that I somehow missed earlier. Oh and I changed plot to surf :-)

[Star Strider]

As always, my pleasure!

My using plot instead of surf was an oversight. My apologies! (I need to proofread my code here before posting it.)

Answer 2

[KSSV]

Refer this link: https://in.mathworks.com/matlabcentral/answers/412639-creating-surface-plot-from-a-matrix-with-3-columns?s_tid=srchtitle

If you have more doubts..attach your file.

[Daniel Bozi]

Thank you! My problem is that the data file is quite large (several hundred rows), so I need some commands that instructs MatLab that VarName1 and VarName2 are x and y respectively, while VarName3 is the z-coordinate. The surface and mesh plot options are not available since MatLab does not recognise the x and y columns as coordinates, and VarName3 as entries in a matrix.

Here is what the start of the file looks like:

[Daniel Bozi]

btw just to add, the matrix would be of size 21x21 (sqrt(441) which is the table size)

[KSSV]

Read about @doc:readtable