How do I plot three columns of data (x, y, dependent_variable)?

Hello,

I have three columns of data in a .dat file I imported into Matlab. The first column is the x coordinate value, the second column is the y coordinate value, and the third column is the data point, which is dependent on both the x and y coordinates.

How do I plot the third column of data versus the first two columns (x and y coordinates)?

Thanks very much for any advice.

Answer 1

[Titus Edelhofer]

Hi,

in your case usually a 3D view is the natural one. Alternatives would be to show the third column as the color (using scatter), something like

scatter(x, y, 10, z)

Or use contour, if isolines make sense for your data.

Titus

Answer 2

[Star Strider]

Three options, depending on what you want: stem3, scatter3 or plot3 functions. (I prefer stem3 because it locates the position of the z data with respect to x and y.)

[Star Strider]

Gabriel’s ‘Answer’ moved here...

Thanks Star Strider.

All of the above commands still give me 3D views of the data. I'm looking for a 2D representation of the data.

Any ideas?

[Star Strider]

You didn’t say that in your initial Question.

I agree with Titus. With the 2D constraint, I can’t think of anything better.

Otherwise:

figure(1)
subplot(2,1,1)
plot(x, z)
subplot(2,1,2)
plot(y, z)

Answer 3

[Sean de Wolski]

If you want to view 3d data (spatial, spatial, value) in two d, you could use color in scatter to represent z and x/y for x/y.

>> scatter(1:10,rand(1,10),50,rand(1,10),'*')