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"Some utility methods" |
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from __future__ import division |
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import numpy as np |
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from numpy import cos |
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from numpy import pi |
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from numpy import sin |
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from astropy.coordinates import Angle |
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from astropy.units import Quantity |
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from astropy.units.core import UnitConversionError |
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def parse_DM(in_DM): |
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""" Convert, as necessary, DM into float |
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""" |
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if isinstance(in_DM, float): |
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DM = in_DM |
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elif isinstance(in_DM, Quantity): |
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DM = in_DM.to('pc/cm**3').value |
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else: |
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raise IOError("Bad format for input DM") |
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# Return |
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return DM |
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def parse_lbd(in_l, in_b, in_d): |
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""" Convert, as necessary, l,b,d into floats |
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Parameters |
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---------- |
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in_l : float or Angle |
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Galactic longitude; assumed deg if unitless |
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in_b : float |
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Galactic latitude; assumed deg if unitless |
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in_d : float or Quantity |
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Distance to source; assumed kpc if unitless |
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Returns |
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------- |
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l : float |
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b : float |
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d : float |
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Distance in kpc |
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""" |
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# l |
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if isinstance(in_l, float): |
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l = in_l |
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elif isinstance(in_l, int): |
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l = float(in_l) |
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elif isinstance(in_l, (Angle,Quantity)): |
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l = in_l.value |
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else: |
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raise IOError("Bad format for input Galactic longitude") |
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# b |
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if isinstance(in_b, float): |
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b = in_b |
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elif isinstance(in_b, int): |
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b = float(in_b) |
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elif isinstance(in_b, (Angle,Quantity)): |
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b = in_b.value |
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else: |
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raise IOError("Bad format for input Galactic latitude") |
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# d |
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if isinstance(in_d, float): |
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d = in_d |
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elif isinstance(in_d, int): |
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d = float(in_d) |
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elif isinstance(in_d, (Quantity)): |
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d = in_d.to('kpc').value |
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else: |
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raise IOError("Bad format for input distance") |
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# Return |
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return l,b,d |
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def galactic_to_galactocentric(l, b, distance, xyz_sun): |
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slc = sin(l/180*pi) |
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clc = cos(l/180*pi) |
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sbc = sin(b/180*pi) |
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cbc = cos(b/180*pi) |
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rgalc = distance*cbc |
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xc = xyz_sun[0] + rgalc*slc |
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yc = xyz_sun[1] - rgalc*clc |
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zc = xyz_sun[-1] + distance*sbc |
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return np.array([xc, yc, zc]) |
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def lzproperty(attribute): |
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""" |
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Lazy property: evaluate property only once |
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""" |
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save_att = '_' + attribute.__name__ |
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@property |
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def _get(self): |
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try: |
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return getattr(self, save_att) |
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except AttributeError: |
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setattr(self, save_att, attribute(self)) |
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return getattr(self, save_att) |
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return _get |
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def rotation(theta, axis=-1): |
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""" |
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Return a rotation matrix around axis |
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0:x, 1:y, 2:z |
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""" |
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ct = cos(theta) |
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st = sin(theta) |
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if axis in (0, -3): |
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return np.array([[1, 0, 0], |
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[0, ct, st], |
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[0, -st, ct]]) |
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if axis in (1, -2): |
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return np.array([[ct, 0, st], |
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[0, 1, 0], |
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[-st, 0, ct]]) |
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if axis in (2, -1): |
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return np.array([[ct, st, 0], |
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[-st, ct, 0], |
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[0, 0, 1]]) |
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