how to plot a scattered heat map

Hi,

I have 2 vectors from a table, and I'd like to create chart similar to the one in the picture. I didn't found any matlab of the shelf command for it, is there is a way that I can

[Mohammad Sami]

Something like this perhaps ?

https://www.mathworks.com/matlabcentral/answers/89665-generating-an-array-of-hexagonal-shape-pattern

[sani]

I don't want the hexagonal plotting, just the heatmap coloring on a regular scattered plot (I will replace the image to something more similar to what I need)

[Mohammad Sami]

Yes the scatter function will work for that.

scatter(x,y,size,color).

If you don't have size you can leave it empty.

scatter(x,y,[],color).

Use colormap to change the coloring scheme if you need to.

Answer 1

[Image Analyst]

Mohammad is right. Make a colormap, such as jet or hsv, and build a color table where for each value of your data, you assign the corresponding color from the colormap. Easy. Attach your data if you can't do it and someone will for you. Something like this untested code:

cmap = jet(256);
v = rescale(yourValues, 1, 256); % Nifty trick!
numValues = length(yourValues)
markerColors = zeros(numValues, 3)
% Now assign marker colors according to the value of the data.
for k = 1 : numValues
    row = round(v(k));
    markerColors(k, :) = cmap(row, :);
end
% Create the scatter plot.
scatter(x, y, [], markerColors);
grid on;

[Charlie Hillary]

Hi! Could you specify what yourValues and numValues are?

I have a 3 column matrix with the third being the colour value like so:

Where

dat =  [0	21	1.07	;
0	60	0.51	;
0	81	0.74	;
0	102	0.84	;
0	151	0.96	;
0	201	1.26	;
0	300	1.08	;
0	387	1.31	;
0	501	1.44	;
0	589	1.4	;
0	693	1.39	;
0	792	1.25	;
0	889	1.16	;
0	990	1.07	;
0	1185	1.21	;
0	1384	1.14	;
0	1582	1.44	;
0	1778	1.42	;
0	1976	0.69	;
0	2466	1.04	;
0	2957	1.64	;
0	3201	0.94	;
0	3521	0.82	;
48.8	19	1.01	;
48.8	37	0.37	;
48.8	50	0.47	;
48.8	75	0.63	;
48.8	99	0.75	;
48.8	119	0.57	;
48.8	137	3.04	;
74.8	21	0.73	;
74.8	39	0.34	;
74.8	71	0.52	;
74.8	149	0.6	];

How would I adapt this:

cmap = jet(256);
v = rescale(myVal, 1, 256); % Nifty trick!
numValues = length(myVal)
markerColors = zeros(numVal, 3)
% Now assign marker colors according to the value of the data.
for k = 1 : numVal
    row = round(v(k));
    markerColors(k, :) = cmap(row, :);
end
% Create the scatter plot.
scatter(x, y, [], markerColors);
grid on;

To work with my data?

Charlie

[Image Analyst]

What does dat represent? A colormap? Or (x,y,z) spatial coordinates?

[Wen Chuan Chong]

Hi!

I have 4 variables (x,y,z,energy) and I would like the colour to be on the energy variable. Can you advise on how I would achieve this?

Best regards,

Jacob

[Image Analyst]

@Wen Chuan Chong, can you attach your 4 variables in a .mat file in a new question?

save('answers.mat', 'x', 'y', 'z', 'energy');

That way we'll have something to work with. In the meantime, see my attached example.