Introduce power colors

[matteobachetti]

This PR introduces Power colors à la Heil et al. 2015. Now we can calculate power colors (both linear and logarithmic) and the hue, also defined according to the same paper by Heil+. I added the relevant functions in fourier.py, and tested them in test_fourier.py
Moreover, Power colors can be directly calculated from the spectra in a DynamicalCrossspectrum or DynamicalPowerspectrum, with the new methods power_colors.

In order to make power colors more usable, we also needed a simple way to combine contiguous power spectra to improve the S/N. I added a function to DynamicalCrossspectrum to combine n contiguous spectra together, regardless of their distance in time (e.g. two intervals on the opposite side of an occultation in NICER).

Demonstration here: StingraySoftware/notebooks#76

[codecov]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (cc9d575) 96.31% compared to head (83681ca) 96.40%.
Report is 37 commits behind head on main.

Files	Patch %	Lines
stingray/lightcurve.py	83.33%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #780      +/-   ##
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+ Coverage   96.31%   96.40%   +0.08%     
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  Files          43       43              
  Lines        8495     8697     +202     
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+ Hits         8182     8384     +202     
  Misses        313      313              

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[dhuppenkothen]

Yay! Looks great! I only have minor comments, so I'll pre-emptively approve it so that it can get merged once everything is fixed.

[dhuppenkothen]

Given that there is an uncertainty on the power colours, should there also be an uncertainty on the hue?

[matteobachetti]

It's just tricky to compute, because both error bars matter here (x and y), and I don't think people use the error bars on hues much anyway? Anyways, open to figure this out

[pep8speaks]

Hello @matteobachetti! Thanks for updating this PR. We checked the lines you've touched for PEP 8 issues, and found:

• In the file stingray/base.py:

Line 2254:81: E203 whitespace before ':'
Line 2255:60: E203 whitespace before ':'
Line 2266:81: E203 whitespace before ':'
Line 2267:60: E203 whitespace before ':'

• In the file stingray/crossspectrum.py:

Line 2033:101: E501 line too long (101 > 100 characters)

Comment last updated at 2024-01-11 16:51:45 UTC