draw.sector(
    start.degree = 0,
    end.degree = 360,
    rou1 = 1,
    rou2 = NULL,
    center = c(0, 0),
    clock.wise = TRUE,
    col = NA,
    border = "black",
    lwd = par("lwd"),
    lty = par("lty"))

plot(c(-1, 1), c(-1, 1), type = "n", axes = FALSE, ann = FALSE, asp = 1)
draw.sector(20, 0)
draw.sector(30, 60, rou1 = 0.8, rou2 = 0.5, clock.wise = FALSE, col = "#FF000080")
draw.sector(350, 1000, col = "#00FF0080", border = NA)
draw.sector(0, 180, rou1 = 0.25, center = c(-0.5, 0.5), border = 2, lwd = 2, lty = 2)
draw.sector(0, 360, rou1 = 0.7, rou2 = 0.6, col = "#0000FF80")

sectors = letters[1:8]
circos.initialize(sectors, xlim = c(0, 1))
for(i in 1:3) {
    circos.trackPlotRegion(ylim = c(0, 1))
}
circos.info(plot = TRUE)

draw.sector(get.cell.meta.data("cell.start.degree", sector.index = "a"),
            get.cell.meta.data("cell.end.degree", sector.index = "a"),
            rou1 = 1, col = "#FF000040")

draw.sector(0, 360,
    rou1 = get.cell.meta.data("cell.top.radius", track.index = 1),
    rou2 = get.cell.meta.data("cell.bottom.radius", track.index = 1),
    col = "#00FF0040")

draw.sector(get.cell.meta.data("cell.start.degree", sector.index = "e"),
            get.cell.meta.data("cell.end.degree", sector.index = "f"),
            get.cell.meta.data("cell.top.radius", track.index = 2),
            get.cell.meta.data("cell.bottom.radius", track.index = 3),
            col = "#0000FF40")

pos = circlize(c(0.2, 0.8), c(0.2, 0.8), sector.index = "h", track.index = 2)
draw.sector(pos[1, "theta"], pos[2, "theta"], pos[1, "rou"], pos[2, "rou"],
    clock.wise = TRUE, col = "#00FFFF40")
circos.clear()