class healpy.rotator.Rotator(rot=None, coord=None, inv=None, deg=True, eulertype='ZYX')

Rotation operator, including astronomical coordinate systems.

This class provides tools for spherical rotations. It is meant to be used in the healpy library for plotting, and for this reason reflects the convention used in the Healpix IDL library.


rot : None or sequence

Describe the rotation by its euler angle. See euler_matrix_new().

coord : None or sequence of str

Describe the coordinate system transform. If rot is also given, the coordinate transform is applied first, and then the rotation.

inv : bool

If True, the inverse rotation is defined. (Default: False)

deg : bool

If True, angles are assumed to be in degree. (Default: True)

eulertype : str

The Euler angle convention used. See euler_matrix_new().


>>> r = Rotator(coord=['G','E'])  # Transforms galactic to ecliptic coordinates
>>> theta_gal, phi_gal = np.pi/2., 0.
>>> theta_ecl, phi_ecl = r(theta_gal, phi_gal)  # Apply the conversion
>>> print(theta_ecl)
>>> print(phi_ecl)
>>> theta_ecl, phi_ecl = Rotator(coord='ge')(theta_gal, phi_gal) # In one line
>>> print(theta_ecl)
>>> print(phi_ecl)
>>> vec_gal = np.array([1, 0, 0]) #Using vectors
>>> vec_ecl = r(vec_gal)
>>> print(vec_ecl)
[-0.05488249 -0.99382103 -0.09647625]


mat The matrix representing the rotation.
coordin The input coordinate system.
coordout The output coordinate system.
coordinstr The input coordinate system in str.
coordoutstr The output coordinate system in str.
rots The sequence of rots defining the rotation.
coords The sequence of coords defining the rotation.


I(*args, **kwds) Rotate the given vector or direction using the inverse matrix.
__call__(*args, **kwds) Use the rotator to rotate either spherical coordinates (theta, phi) or a vector (x,y,z).
angle_ref(*args, **kwds) Compute the angle between transverse reference direction of initial and final frames
do_rot(i) Returns True if rotation is not (close to) identity.