How to plot scatter graph with colourmap functon

Hi,

I have this 3 column matrix, where:

column 1 = x values

column 2 = y values

columnn 3 = value of each given point

myVal = [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	;
74.8	200	0.89	;
74.8	300	0.56	;
74.8	398	0.74	;
74.8	496	0.81	;
74.8	596	0.86	;
74.8	694	1.03	;
74.8	792	0.85	;
282.7	15	0.12	;
282.7	54	0.19	;
282.7	80	0.18	;
282.7	100	0.24	;
282.7	199	0.29	;
282.7	497	0.56	;
282.7	695	0.76	];

How would I adapt this data to work for this scatter heatmap function:

cmap = jet(256); %state colourmaop
v = rescale(myVal, 1, 256);
numVal = 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;

Charlie

[KSSV]

x = myVal(:,1) ; 
y = myVal(:,2) ;
z = myVal(:,3) ; 
scater(x,y,[],z,'filled')
colorbar

[Charlie Hillary]

Ok. I get this error 'Index in position 2 exceeds array bounds (must not exceed 2).'. How so? as the value is 3

[Charlie Hillary]

Got it working dont worry

Answer 1

[Ameer Hamza]

Try this

x = myVal(:,1);
y = myVal(:,2);
z = myVal(:,3);

cmap = jet(256); %state colourmaop
min_val = min(z);
max_val = max(z);

colors = interp1(linspace(min_val, max_val, 256), cmap, z);
scatter(x, y, [], colors);

[Charlie Hillary]

Ok. I get an error for the z value, as this value is not supposed to exceed 2?

[Charlie Hillary]

Note that my actually data file is much bigger than I stated. It works for this smaller data value though

[Ameer Hamza]

Can you explain what do you mean by "I get an error for the z value, as this value is not supposed to exceed 2". What is the error message?

Answer 2

[Bjorn Gustavsson]

To make it short and simple couldn't you just use scatter and let it automatically scale the values?

scatter(x,y,23,myVal,'filled')
colormap(jet(256))

[Charlie Hillary]

Yes this works too, thanks