Python conversion between coordinates

Question

Are there functions for conversion between different coordinate systems?

For example, Matlab has [rho,phi] = cart2pol(x,y) for conversion from cartesian

Answer 1

The existing answers can be simplified:

from numpy import exp, abs, angle

def polar2z(r,theta):
    return r * exp( 1j * theta )

def z2polar(z):
    return ( abs(z), angle(z) )

Or even:

polar2z = lambda r,θ: r * exp( 1j * θ )
z2polar = lambda z: ( abs(z), angle(z) )

Note these also work on arrays!

rS, thetaS = z2polar( [z1,z2,z3] )
zS = polar2z( rS, thetaS )