'Returns SVG path element for the LinearEntity.
Parameters
scale_factor : float
Multiplication factor for the SVG stroke-width.  Default is 1.
fill_color : str, optional
Hex string for fill color. Default is "#66cc99".'

def _svg(self, scale_factor=1.0, fill_color='#66cc99'):

    from sympy.core.evalf import N
    verts = (N(self.p1), N(self.p2))
    coords = ['{0},{1}'.format(p.x, p.y) for p in verts]
    path = 'M    {0}    L    {1}'.format(coords[0], '    L    '.join(coords[1:]))
    return '<path    fill-rule="evenodd"    fill="{2}"    stroke="#555555"    stroke-width="{0}"    opacity="0.6"    d="{1}"    marker-start="url(#markerCircle)"    marker-end="url(#markerArrow)"/>'.format((2.0 * scale_factor), path, fill_color)
