def writePolys(pl, f):
    """Write a list of polygons pl into the file f.
    The result is under the form [[[ra1, de1],[ra2, de2],[ra3, de3],[ra4, de4]], [[ra1, de1],[ra2, de2],[ra3, de3]]]"""
    f.write('[')
    for idx, poly in enumerate(pl):
        f.write('[')
        for iv, v in enumerate(poly):
            f.write('[%.8f, %.8f]' % (v[0], v[1]))
            if iv != len(poly) - 1:
                f.write(', ')
        f.write(']')
        if idx != len(pl) - 1:
            f.write(', ')
    f.write(']')