Remove get_shower_coordinates from CameraGeometry

[kosack]

the CameraGeometry.get_shower_coordinates() code seems out of place - the instrument module is not for algorithms, but for describing the hardware, and I don't like mixing the concepts too much.

I suggest we move this function elsewhere . It seems to just be a coordinate transform, so could be a new Frame (it's just a rotated camera). Or because it's only used by image.get_timing_parameters() and image.concentration()`, but nowhere else, it could be a helper-function in the image module.

ctapipe/ctapipe/instrument/camera.py

Lines 494 to 519 in 1322e2f

	def get_shower_coordinates(self, x, y, psi):
	'''
	Return longitudinal and transverse coordinates of the pixels
	for a given set of hillas parameters
	Parameters
	----------
	hillas_parameters: ctapipe.io.containers.HilllasContainer
	Returns
	-------
	longitudinal: astropy.units.Quantity
	longitudinal coordinates (along the shower axis)
	transverse: astropy.units.Quantity
	transverse coordinates (perpendicular to the shower axis)
	'''
	cos_psi = np.cos(psi)
	sin_psi = np.sin(psi)
	delta_x = self.pix_x - x
	delta_y = self.pix_y - y
	longi = delta_x * cos_psi + delta_y * sin_psi
	trans = delta_x * -sin_psi + delta_y * cos_psi
	return longi, trans

[maxnoe]

Agreed. It might also be better es a more general method taking arbitrary x and y instead of the pixel positions