# paste this code at the end of VectorFieldPlot 1.0
doc = FieldplotDocument('VFPt_cylindrical_magnets_antiparallel', width=600, height=600, commons=True)
field = Field({'coils':[[0, -0.75, 0, 0.25, 0.75, -1], [0, 0.75, 0, 0.25, 0.75, 1]]})
doc.draw_magnets(field)
n = 11
for i, y0 in ([[j, -0.75] for j in range(n)] +
    [[j, 0.75] for j in range(n-4, n)]):
    a = -0.25 + 0.5 * (0.5 + i) / n
    line = FieldLine(field, [0., a + y0],
        directions='both', maxr=20.0)
    dist = 1.3
    if i == n - 4 or i == n - 6: dist = 1.5
    doc.draw_line(line, arrows_style={'dist':dist, 'offsets':[1., .5, .5, 1.]})
doc.write()