Visualize population data in a coordinate grid

Hi,

I'm struggling with the imagesc function to plot my population data.

I have a matrix A of 1500 x 3, in which the first column contains the decimal degree latitude value, the second column contains the decimal degree longitude value and the third column contains the population count at that specific coordinate set.

Now I would like to make the population visible in a plot with the x-axis showing the longitude and the y-axis the latitude coordinate.

Matrix A looks like this:

A= [51.5416665650000  -0.650000374000000  236;
51.5416665650000  -0.641667041000000  519;
51.5416665650000  -0.633333708000000  1857............]

Answer 1

[Star Strider]

See if this does what you want:

A= [51.5416665650000  -0.650000374000000  236;
51.5416665650000  -0.641667041000000  519;
51.5416665650000  -0.633333708000000  1857];

figure(1)
scatter3(A(:,1), A(:,2), A(:,3))
grid on

figure(2)
stem3(A(:,1), A(:,2), A(:,3))
grid on

[Bas]

Thanks for your reply.

Actually I'm looking for some sort of 2D plot with colors instead of a 3D plot. Can you help me further?

[Star Strider]

My pleasure.

You have two independent coordinates, latitude and longitude. A 3D plot would be best to show them.

A 2D plot would mean that you would have to not use one of your independent coordinates. How would you want a 2D plot to look?

[Bas]

What I'm looking for is a 2D plot with on the x-axis the longitude coordinate, on the y-axis the latitude coordinate and the grid itself showing the population by means of a colorbar (darker color, a higher population density).

So the grid should be minimum longitude and latitude coordinate in the origin and the maximum longitude and latitude coordinate in the northeast corner.

[Star Strider]

Experiment with the image function and its friends:

figure(3)
image(A(:,1), A(:,2), A(:,3))

Note that the related pcolor function will delete one row and one column, because of the way it defines its plots. I do not recommend it for what you want to do.