Same script to compute and replot spectra

[erwanp]

🎯 Describe what you'd like

Ever happened that you computed a spectrum, plotted it, then need to re-plot it few months later and therefore need to recompute it ? What if the spectrum took several minutes to compute ?

• SpectrumFactory already comes with a feature that connects it to a SpecDatabase (a folder of Spectrum objects) which initially checks that the Spectrum exists, returns it if it does, or recomputes and add to the folder if it does not

We could have a similar feature for calc_spectrum that automatically saves to a file, and retrieves from the file if it's there already.

💡 Possible implementations

1. we give an output filename to calc_spectrum.
2. if filename exists :

• load the spec
• check that metadata correpsond to computational conditions
• if not > error or recompute
• if yes > return the Spectrum directly

3. else:

• compute, and save

s = calc_spectrum(Tgas=... ,   output_file='blabla.spec', **kwargs)
s.plot()

Edit : there is already a "save_to" parameter in calc_spectrum.

Questions :

• what store parameters to use ? Allow other parameters to be given in **kwargs ? (note : saving all lines is probably a bad idea --> if this feature is used in a loop with spectra with millions of lines this would quickly use all of the disk space !)

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[dcmvdbekerom]

What about we couple it with pypdfplot 😁?

[erwanp]

I had forgotten about this amazing library ! (you should post it on Reddit btw, you are the living proof that it worked for RADIS ! :) ).

It sounds a bit trickier than the simple implementation I suggested above, and will answer a slightly different need. But it also bring new opportunities : one could actually share a Spectrum under .pdf, and just have to rename it to .py to be able to access the script and replot it !

Btw, could pypdfplot support .svg ? Because Word does, and that would be a perfect alternative to Origin. Should I open an Issue there ?

[minouHub]

Nice idea, but it seems that you already implemented it in radis.database ?

[dcmvdbekerom]

[ regarding pypdfplot: go ahead and open an issue! although chances are slim... I will make a reddit post when I finish the matplotlib backend so you can use it by just calling plt.savefif() ]

One way to save plots for later that could be useful is pickling the matplotlib figure:

with open('figure.fig','wb') as f:
    pickle.dump(plt.gcf(),f)

Of course this is just for short term fix, because the spectrumfactory object would be lost in this case.
It does however let you change colors/sizes/axes limits of the plot without rerunning the code.

[erwanp]

See arunavabasu-03/radis-app#619 (comment) for new requirements