Turning off specgram auto-plotting in Jupyter notebook

Question

I'm using Matplotlib's specgram function, which has a form like:

Pxx, freqs, bins, im = specgram(x, NFFT=NFFT, Fs=Fs, noverlap=900)

where Pxx, freqs, bins, and im represent the periodogram, frequency vector, center of time bins, and the image.AxesImage instance. Additionally, you can feed in arguments (**kwargs) that get passed onto imshow.

I cannot seem to use specgram in a Jupyter Notebook, without producing a plot automatically. What argument can I pass into specgram that will stop it from plotting automatically?

I am not calling any plt.show() command. I've tried adding a semi-colon at the end of the line, and I've tried setting the final argument (im) as nothing, like this:

Pxx, freqs, bins, _ = specgram(x, NFFT=NFFT, Fs=Fs, noverlap=900);

but nothing seems to work.

Answer 1

From the PyPlot.jl docs: https://github.com/JuliaPy/PyPlot.jl#non-interactive-plotting

If you use PyPlot from an interactive Julia prompt, such as the Julia command-line prompt or an IJulia notebook, then plots appear immediately after a plotting function (plot etc.) is evaluated.

However, if you use PyPlot from a Julia script that is run non-interactively (e.g. julia myscript.jl), then Matplotlib is executed in non-interactive mode: a plot window is not opened until you run show() (equivalent to plt.show() in the Python examples).

See the docs linked above for further reference.