1引言
在 circlize 参考文档中,作者有一部分介绍了 nested zooming 的部分,主要来放大展示一些区域的具体图形,在数据量多,图形拥挤的时候使用非常有效,用来突出重要区域的部分,下面是示例图形:
仔细观察图形可以看到由两层 track 组成, 放大的区域扇区的大小不会相互重叠,里面应该是有一些计算在的。我们可以参考这个来写一个 arcNestedZoomGrob, 我这里想的是放大的区域和原本扇区相同,这样每一个 sector 就可以避免重叠了, 然后主要思路是绘制 三个图形(上: 原本数据的突出区域, 中: 连接的图形, 下: 放大的区域) 。此外你还需要在放大的区域重新绘制原来图形位置的具体图形。感觉还是比较复杂的。
2arcNestedZoomGrob
参数
arcNestedZoomGrob <- function(x = NULL,y = NULL,
start = 60,end = 120,
r0 = 0.8,r1 = 1,
x0 = 0,y0 = 0,
zoom.start = NULL,
zoom.end = NULL,
zoom.start.x = NULL,
zoom.end.x = NULL,
extend.start = 0,
extend.end = 0,
nested.r = 0.03,
panel.gap = 0.02,
panel.fun = NULL,
zoom.panel.height = NULL,
sub.zoom.gap = 3,
pos = c("bottom","top"),n = 100,
nested.upper.gp = gpar(fill = alpha("white",0.2)),
nested.middle.gp = NULL,
nested.bottom.gp = NULL,
extend.xscale = 0.05,
extend.yscale = 0.05,
clock.wise = FALSE,
name = NULL,gp = NULL, vp = NULL,...)绘图
下面我们展示一下 arcNestedZoomGrob 能绘制成什么样,先绘制基本图形:
newpage()
grid.draw(arcSectorGrob(start = 0,end = 180,
r0 = 0.8,r1 = 1,
add.xaxis = F,add.yaxis = F))
grid.draw(arcPointGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.8,r1 = 1))
grid.draw(arcAxisGrob(start = 0,end = 180,
r0 = 0.8,r1 = 1,
axis.type = "x",pos = "top",
breaks.n = 8,nice.facing = T,
xscale = range(mtcars$mpg)))
然后指定放大区域 (以具体角度指定):
grid.draw(arcNestedZoomGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.8,r1 = 1,
zoom.start = c(30,60,100),
zoom.end = c(50,90,130)))
默认是不绘制图形的,你需要指定 panel.fun 参数提供绘图的函数:
grid.draw(arcNestedZoomGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.8,r1 = 1,
# clock.wise = T,
zoom.start = c(30,60,100),
zoom.end = c(50,90,130),
panel.fun = function(...){
# print(list(...))
arcPointGrob(...)
}))
假如你要修改 arcPointGrob 的其它参数:
grid.draw(arcNestedZoomGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.8,r1 = 1,
zoom.start = c(60),
zoom.end = c(90),
panel.fun = function(...){
args.lst <- list(...)
args.lst <- modifyList(args.lst,list(r0 = 0.2,r1 = 0.3))
do.call(arcPointGrob,args.lst)
}))
你还可以添加多个图层,用 gList 打包一下:
grid.draw(arcNestedZoomGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.8,r1 = 1,
# clock.wise = T,
zoom.start = c(30,60,100),
zoom.end = c(50,90,130),
panel.fun = function(...){
gList(arcPointGrob(...),
arcLinesGrob(...,lines.gp = gpar(lty = "dashed")))
}))
修改颜色:
grid.draw(arcNestedZoomGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.8,r1 = 1,
# clock.wise = T,
zoom.start = c(30,60,100),
zoom.end = c(50,90,130),
panel.fun = function(...){arcPointGrob(...)},
nested.upper.gp = gpar(fill = alpha("red",0.2)),
nested.middle.gp = gpar(fill = alpha("orange",0.5)),
nested.bottom.gp = gpar(fill = alpha("purple",0.5))))
当然你可以指定具体的 x 坐标 (zoom.start.x, zoom.end.x):
grid.draw(arcNestedZoomGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.8,r1 = 1,
panel.fun = function(...){arcPointGrob(...)},
nested.upper.gp = gpar(fill = alpha("red",0.2)),
nested.middle.gp = gpar(fill = alpha("orange",0.5)),
nested.bottom.gp = gpar(fill = alpha("purple",0.5)),
zoom.start.x = c(12,18,22,30),
zoom.end.x = c(15,22,26,30.5)))
修改位置:
newpage()
grid.draw(arcSectorGrob(start = 0,end = 270,
r0 = 0.4,r1 = 0.7,
add.xaxis = F,add.yaxis = F))
grid.draw(arcPointGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 270,
r0 = 0.4,r1 = 0.7))
grid.draw(arcAxisGrob(start = 0,end = 270,
r0 = 0.4,r1 = 0.7,
axis.type = "x",pos = "bottom",
breaks.n = 8,nice.facing = T,
xscale = range(mtcars$mpg)))
grid.draw(arcNestedZoomGrob(x = mtcars$mpg,y = mtcars$disp,
start = 0,end = 180,
r0 = 0.4,r1 = 0.7,
panel.fun = function(...){arcPointGrob(...)},
nested.upper.gp = gpar(fill = alpha("red",0.2)),
nested.middle.gp = gpar(fill = alpha("orange",0.5)),
nested.bottom.gp = gpar(fill = alpha("purple",0.5)),
zoom.start.x = c(12,18,22,30),
zoom.end.x = c(15,22,26,30.5),
pos = "top"))
要让它变成一个 geom 图层感觉还没什么思路,关键在那放大区域的图层该怎么写才比较完美。
3结尾
路漫漫其修远兮,吾将上下而求索。
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