External Group Functions

group_funcs.get_full_mass_radius(radii, ptype, binary)

Get full mass radius for a set of particles.

Parameters

• radii (np.ndarray[::-1]) – Radii of particles

• ptype (np.ndarray[::-1]) – Array of integers containing the particle types.

• binary (int) – Integer used to select particle types. For example, if you are interested in particle types 0 and 3 this value would be 2^0+2^3=9.

Notes

This function iterates forward through the array, so it is advisable to reverse the radii & ptype arrays before passing them via np.ndarray[::-1].

group_funcs.get_half_mass_radius(mass, radii, ptype, half_mass, binary)

Get half mass radius for a set of particles.

Parameters

• mass (np.ndarray) – Masses of particles.

• radii (np.ndarray) – Radii of particles.

• ptype (np.ndarray) – Array of integers containing the particle types.

• half_mass (double) – Half mass value to accumulate to.

• binary (int) – Integer used to select particle types. For example, if you are interested in particle types 0 and 3 this value would be 2^0+2^3=9.

group_funcs.get_periodic_r(boxsize, center, pos, r)

Get periodic radii.

Parameters

• boxsize (double) – The size of your domain.

• center (np.ndarray([x,y,z])) – Position in which to calculate the radius from.

• pos (np.ndarray) – Nx3 numpy array containing the positions of particles.

• r (np.array) – Empty array to fill with radius values.

group_funcs.get_virial_mr(Density, r, mass, collectRadii)

Get virial mass and radius.

Parameters

• Density (array) – Different densities you are interested in: e.g rho200, rhovirial, … They have to be in ascending order.

• r (array) – Particle radii inward

• mass (array) – Cumulative Particle masses inward

• collectRadii (array) – Empty array to contain the radii Should be the same size as the Densities

group_funcs.rotator(vals, Rx, Ry, ALPHA, BETA)

Rotate a number of vectors around ALPHA, BETA

Parameters

• vals (np.ndarray) – Nx3 np.ndarray of values you want to rotate.

• Rx (np.ndarray) – 3x3 array used for the first rotation about ALPHA. The dot product is taken against each value: vals[i] = np.dot(Rx, vals[i])

• Ry (np.ndarray) – 3x3 array used for the second rotation about BETA The dot product is taken against each value: vals[i] = np.dot(Ry, vals[i])

• ALPHA (double) – Angle to rotate around first.

• BETA (double) – Angle to rotate around second.

Notes

This is typically called from utils.rotator().