如何在点阵bwplot中获得框矩形的交替颜色？

Question

当我执行以下代码时(数据集是格子包的一部分)：

ngroups <- length(unique(barley$site)) + 1

bwplot(yield ~ variety, data = barley, box.width = 1/ ngroups,
       groups = year, scales=(x=list(rot=45)), 
       auto.key = list(points = FALSE, rectangles = TRUE, space = "right"),
       par.settings=list(box.rectangle = list(col=c("red", "green"), lwd=3),
                         superpose.polygon=list(col=c("green", "red"), pch=c(15,15))
                         ),
       panel.groups = function(x, y, ..., group.number) {
         panel.bwplot(x + (group.number-1.5)/ngroups, y, ...)
       },
       panel=function(...) {
         panel.grid(h = -1, v=0)
         panel.superpose(par.settings=list(box.rectangle=list(col=c("green", "red"))),  ...)
       }
      ) 

我得到了下面的图表：

​

​

如何从左到右获得红色和绿色的交替颜色？(我注意到，如果我删除自定义面板，它可以正常工作，但我希望保留灰色参考线。)

谢谢。

Answer 1

如果您愿意使用填充而不是边框来区分年份，我可以为您提供一个解决方案。我还在一个似乎是错误的地方改变了颜色的顺序(？)，并删除了一些冗余的代码。

bwplot(yield ~ variety, data = barley, box.width = 1 / ngroups,
       groups = year, scales = (x = list(rot = 45)),
       par.settings = list(superpose.polygon = list(col = c("green", "red"),
                                                    pch =c (15, 15)),
                         superpose.symbol = list(fill = c("green", "red"))),
       auto.key = list(points = FALSE, rectangles = TRUE, space = "right"),
       panel.groups = function(x, y, ..., group.number) {
         panel.bwplot(x + (group.number - 1.5) / ngroups, y, ...)
       },
       panel = function(...) {
         panel.grid(h = -1, v = 0)
         panel.superpose(...)
       }
) 

​

​