格子 xyplot 不显示 Y 轴上的所有级别的因素：不完整的图

Question

我使用 Lattice 中的 xyplot() 绘制由具有 3 列的数据框定义的箭头：posi（数字）、from（字符）、to（字符）。问题：有时，箭头会超出情节的范围。换句话说，绘图 window 不够大，无法可视化所有数据。

我尝试明确添加因子水平，但无济于事。似乎如果因子 "df$from" 中不存在更极端的水平（例如 "D"），则这些水平不会被计入绘图 window。我查看了 ylim 但这仅限于数值。

我环顾四周，发现了很多关于重新缩放、重新排序轴的内容，但没有帮助我解决手头的问题。这个问题与@skan 的问题有关：.

我的数据：

l <- c("A", "B", "C", "D")
df <- data.frame(posi = c(1, 2, 3, 4, 5), 
                 from = factor(c("A", "B", "C", "D", "A"), levels = l, ordered = TRUE),
                 to = factor(c("C", "D", "D", "C", "A"), levels = l, ordered = TRUE)
)

此图符合预期：

xyplot(from ~ posi , type="p", col="black",  data=df, pch=16, xlim = c(0,7), 
       panel = function(...){
         panel.dotplot(x = df$posi, y = df$from, col ="green", cex=1.6)
         panel.dotplot(x = (df$posi+1), y = df$to, col="black", cex=1.)
         panel.arrows(x0 = df$posi, y0 = df$from, x1 = df$posi+1, y1 = df$to, lwd=2, col="blue" )
       }
)

当我只使用同一数据框的前 3 行且 'old' 因子水平完好无损时，该图没有考虑到稍后需要 "D" 水平。

## only first 3 rows, without element "D" in the factor df$from
df <- df[1:3, ]

导致此情节：

我希望能够设置 Y 轴的范围，如有任何帮助或提示，我将不胜感激。

Answer 1

在对 xyplot 的调用中指定 "drop.unused.levels = FALSE" 可以避免该问题。

library(lattice)

l <- c("A", "B", "C", "D")
df <- data.frame(posi = c(1, 2, 3, 4, 5), 
             from = factor(c("A", "B", "C", "D", "A"), levels = l, 
                           ordered = TRUE),
             to = factor(c("C", "D", "D", "C", "A"), levels = l, 
                         ordered = TRUE))


xyplot(from ~ posi , type="p", col="black",  data=df, pch=16, xlim = c(0,7), 
   panel = function(...){
     panel.dotplot(x = df$posi, y = df$from, col ="green", cex=1.6)
     panel.dotplot(x = (df$posi+1), y = df$to, col="black", cex=1.)
     panel.arrows(x0 = df$posi, y0 = df$from, x1 = df$posi+1, y1 = df$to, 
                  lwd=2, col="blue" )
   })

df2 <- df[1:3,]
xyplot(from ~ posi , type="p", col="black",  data=df2, pch=16, xlim = c(0,7), 
   drop.unused.levels = FALSE,
   panel = function(...){
     panel.dotplot(x = df2$posi, y = df2$from, col ="green", cex=1.6)
     panel.dotplot(x = (df2$posi+1), y = df2$to, col="black", cex=1.)
     panel.arrows(x0 = df2$posi, y0 = df2$from, x1 = df2$posi+1, 
                  y1 = df2$to, lwd=2, col="blue" )
   })

格子 xyplot 不显示 Y 轴上的所有级别的因素：不完整的图

Lattice xyplot does not show all levels of factor on Y axis: incomplete plot

plot

r

lattice