viscid.dipole module

A collection of tools for dipoles

viscid.dipole.guess_dipole_moment(b, r=2.0, strength=32707.5292732387, cap_angle=40, cap_ntheta=121, cap_nphi=121, plot=False)

guess dipole moment from a B field

viscid.dipole.make_dipole(m=(0, 0, -32707.5292732387), strength=None, l=None, h=None, n=None, center='cell', dtype='f8', twod=False, nonuniform=False, crd_system='gse', name='b')

Generate a dipole field with magnetic moment m [x, y, z]

viscid.dipole.fill_dipole(B, m=(0, 0, -32707.5292732387), strength=None, mask=None)

set B to a dipole with magnetic moment m

Parameters:

• B (Field) – Field to fill with a dipole
• m (ndarray, or datetime64-like) – Description
• strength (float) – if given, rescale the dipole moment even if it was given explicitly
• mask (Field) – boolean field as mask, B will be filled where the mask is True

Returns:

B

Return type:

Field

viscid.dipole.calc_dip(pts, m=(0, 0, -32707.5292732387), strength=None, crd_system='gse', dtype=None)

Calculate a dipole field at various points

Parameters:

• pts (ndarray) – Nx3 array of points at which to calculate the dipole. Should use the same crd system as m
• m (sequence, datetime) – dipole moment
• strength (None, float) – If given, rescale m to this magnitude
• crd_system (str) – Something from which cotr can divine the coordinate system for both pts and m. This is only used if m is given as a datetime and we need to figure out the dipole moment at a given time in a given crd system
• dtype (str, np.dtype) – dtype of the result, defaults to the same datatype as pts

Returns:

Nx3 dipole field vectors for N points

Return type:

ndarray

viscid.dipole.set_in_region(a, b, alpha=1.0, beta=1.0, mask=None, out=None)

set ret = alpha * a + beta * b where mask is True

viscid.dipole.make_spherical_mask(fld, rmin=0.0, rmax=None, rsq=None)

make a mask that is True between rmin and rmax

viscid.dipole.xyz2lsrlp(pts, cotr=None, crd_system='gse')

Ceovert x, y, z -> l-shell, r, lambda, phi [sm coords]

• r, theta, phi = viscid.cart2sph(pts in x, y, z)
• lambda = 90deg - theta
• r = L cos^2(lambda)

Parameters:

• pts (ndarray) – 3xN for N (x, y, z) points
• cotr (None) – if given, use cotr to perform mapping to / from sm
• crd_system (str) – crd system of pts

Returns:

4xN array of N (l-shell, r, lamda, phi) points

Return type:

ndarray

viscid.dipole.dipole_map(pts, r=1.0, cotr=None, crd_system='gse', as_spherical=False)

Map pts along an ideal dipole to radius r

lambda = 90deg - theta; r = L cos^2(lambda)

cos^2(lambda) = cos^2(lambda_0) * (r / r_0)

Parameters:

• pts (ndarray) – 3xN for N (x, y, z) points
• r (float) – radius to map to
• cotr (None) – if given, use cotr to perform mapping to / from sm
• crd_system (str) – crd system of pts
• as_spherical (bool) – if True, then the return array is (t, theta, phi) with theta in the range [0, 180] and phi [0, 360] (in degrees)

Returns:

3xN array of N (x, y, z) points all at a distance

r_mapped from the center of the dipole

Return type:

ndarray

viscid.dipole.dipole_map_value(fld, pts, r=1.0, fillna=None, cotr=None, crd_system=None, interp_kind='linear')

Map values assuming they’re constant along ideal dipole lines

Parameters:

• fld (Field) – values to interpolate onto the mapped pts
• pts (ndarray) – 3xN for N (x, y, z) points that will be mapped
• r (float) – radius of resulting map
• cotr (None) – if given, use cotr to perform mapping in sm
• crd_system (str) – crd system of pts
• interp_kind (str) – how to interpolate fld onto source points

Returns:

ndarray of mapped values, one for each of the N points

Return type:

ndarray