Transcribed function for estimating parallel curves (2nd-order polynomials) into Python. Estimation quality on higher order polynomials is not guaranteed.
Original author: Edward Zechmann https://www.mathworks.com/matlabcentral/fileexchange/27873-parallel-curves
"Simple program to generate the inner and outer parallel curves in rectangular coordinates. inner parallel is toward the center of curvature and outer parallel is away from the center of curvature. Use option flag1=0 to keep the parallels on the side sides (disregarding concavity). The Input the x, y coordinate pairs and distance between the curve and the parallels and the option to make a plot."