Proper Labeling of X & Y values Contour Plot

Is there a way to use arrays for labeling the X&Y values of a Contour Plot ..

In this case, Y would be Frequency and X Time ( radio telescope data acq sequence )

[DGM]

How are you using contour? If you're calling contour() with three arguments, it should have ticks and tick labels on both axes already.

Answer 1

[Star Strider]

Use the tick label properties to change the tick labels. Any new tick values have to be in the ranges of the current tick values, so changing them is not likely to produce the desired results.

[X,Y,Z] = peaks(50);

figure
[c,h] = contourf(X, Y, Z);
Ax = gca;                                               % Axes Handle
xt = Ax.XTick                                           % Tick Values

xt = 1×7

-3 -2 -1 0 1 2 3

Ax.YTickLabel = xt*pi;                                  % New Tick Labels
yt = Ax.YTick                                           % Tick Values

yt = 1×7

-3 -2 -1 0 1 2 3

Ax.XTickLabel = yt-min(yt);                             % New Tick Labels
xlabel('Time (units)')
ylabel('Frequency (units)')

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[Star Strider]

Also, if you are doing time-frequency analysis see the pspectrum and spectrogram functions. (The methods and units are different for each of them, so check the documentation to see which one is most appropriate for your data. I generally prefer pspectrum with the 'spectrogram' option.) They could make time-frequency analyses easier.

[Alex Pettit]

GOT IT Nice : Thanks Everyone.

The data is in two column Freq / Ampl pairs from the SDR ( software defined radio ) at a data rate of

3000 FFT blocks per second. I am acquiring 5 minutes of data into one saved set .. consisting of 900,000 averages. Thankfully, I do not need to save the Time data !

FYI

Here is a surface plot of 100 data sets ( FFT 512 elements ) over ~ 8 hour period .

Freq range in the 1.42 GHz Hydrogen RF range .. Doppler shifted due th the relative motion of the Hydrogen clouds & Earth.

It represents a 10 degree wide, 8 hour long slice through the Milky Way and surrounding area

( A new hobby )

Regards,

Alex P

[Star Strider]

My pleasure!

If my Answer helped you solve your problem, please Accept it!

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