Lattice 的 `panel.rug` 产生不同的线长和宽图

Question

当在格子中生成包含 panel.rug() 边距的宽图时，rugged 边距中的线条长度在 y 轴上比 x- 长轴：

library(lattice)
png(width=800, height=400)
xyplot(Fertility ~ Education, swiss, panel = function(x, y,...) {
  panel.xyplot(x, y, col=1, pch=16)
  panel.rug(x, y, col=1, end= ...)})
dev.off()

我希望 x 轴和 y 轴上的那些 rug 线的长度相同，而不管绘图的形状如何（注意：现在 rug 行只有在绘图为正方形时才具有相同的长度）。

Answer 1

使用 lattice，只需将 panel.rug 使用的坐标系从其默认值 ("npc") 更改为 "snpc":

library(lattice)

## png(width=800, height=400)
xyplot(Fertility ~ Education, swiss, panel = function(x, y,...) {
  panel.xyplot(x, y, col=1, pch=16)
  panel.rug(x = x, y = y,  
            x.units = rep("snpc", 2),  y.units = rep("snpc", 2), 
            col=1, end= ...)
})
## dev.off()

要了解为什么这会得到你想要的东西，请参阅?unit了解这两个坐标系的含义：

 Possible ‘units’ (coordinate systems) are:

 ‘"npc"’ Normalised Parent Coordinates (the default).  The origin
      of the viewport is (0, 0) and the viewport has a width and
      height of 1 unit.  For example, (0.5, 0.5) is the centre of
      the viewport.

 ‘"snpc"’ Square Normalised Parent Coordinates.  Same as Normalised
      Parent Coordinates, except gives the same answer for
      horizontal and vertical locations/dimensions.  It uses the
      _lesser_ of npc-width and npc-height.  This is useful for
      making things which are a proportion of the viewport, but
      have to be square (or have a fixed aspect ratio).

Lattice 的 `panel.rug` 产生不同的线长和宽图

Lattice's `panel.rug` produces different line length with wide plot

r

data-visualization

lattice