在rasterVis中打印具有重叠多边形的光栅时的范围问题

我正在开发一个基于

rasterVis:：levelplot

的绘图功能，用户可以将光栅对象或光栅对象和

sf

多边形对象传递到该功能

函数相当复杂，但显示问题的最小子集如下所示：

library(sf)
library(raster)
library(rasterVis)

myplot <- function(in_rast, in_poly = NULL) {
  rastplot <- rasterVis::levelplot(in_rast, margin = FALSE)
  polyplot <- layer(sp::sp.polygons(in_poly))
  print(rastplot + polyplot)
}

并对其功能进行了测试。理论上，我认为这应该是可行的：

my_poly  <- as(my_poly, "Spatial") # convert to spatial
myplot(in_rast, in_poly = my_poly)

有人能解释一下这里发生了什么吗？这显然是（？）一个范围问题，但我真的不明白为什么函数的行为是这样的

---

提前谢谢

latticeExtra:：layer的帮助页面说明：

层中使用的评估是非标准的，一开始可能会让人困惑：您通常引用变量，就像在面板函数中一样（x、y等）；您通常可以引用存在于全局环境（工作区）中的对象，但在数据参数中将它们按名称传递给图层更安全

在函数中使用

层

时，可以将对象嵌入列表中，并将其传递到

数据

参数中：

myplot <- function(in_rast, in_poly = NULL) {
  rastplot <- levelplot(in_rast, margin = FALSE)
  polyplot <- layer(sp.polygons(x), 
                    data = list(x = in_poly))
  print(rastplot + polyplot)
}

in_poly <- my_poly
in_poly <- as(in_poly, "Spatial")
myplot(in_rast, in_poly = in_poly)

in_poly <- structure(list(cell_id = 1:4, geometry = structure(list(structure(list(
    structure(c(0, 0.5, 0.5, 0, 0, 0, 0, 0.5, 0.5, 0), .Dim = c(5L, 
    2L))), class = c("XY", "POLYGON", "sfg")), structure(list(
    structure(c(0.5, 1, 1, 0.5, 0.5, 0, 0, 0.5, 0.5, 0), .Dim = c(5L, 
    2L))), class = c("XY", "POLYGON", "sfg")), structure(list(
    structure(c(0, 0.5, 0.5, 0, 0, 0.5, 0.5, 1, 1, 0.5), .Dim = c(5L, 
    2L))), class = c("XY", "POLYGON", "sfg")), structure(list(
    structure(c(0.5, 1, 1, 0.5, 0.5, 0.5, 0.5, 1, 1, 0.5), .Dim = c(5L, 
    2L))), class = c("XY", "POLYGON", "sfg"))), n_empty = 0L, class = c("sfc_POLYGON", 
"sfc"), precision = 0, crs = structure(list(epsg = NA_integer_, 
    proj4string = NA_character_), .Names = c("epsg", "proj4string"
), class = "crs"), bbox = structure(c(0, 0, 1, 1), .Names = c("xmin", 
"ymin", "xmax", "ymax")))), .Names = c("cell_id", "geometry"), row.names = c(NA, 
4L), class = c("sf", "data.frame"), sf_column = "geometry", 
agr = structure(NA_integer_, class = "factor", .Label = c("constant", 
"aggregate", "identity"), .Names = "cell_id"))


in_poly  <- as(in_poly, "Spatial")
myplot(in_rast, in_poly = in_poly)

myplot <- function(in_rast, in_poly = NULL) {
  rastplot <- levelplot(in_rast, margin = FALSE)
  polyplot <- layer(sp.polygons(x), 
                    data = list(x = in_poly))
  print(rastplot + polyplot)
}

myplot(in_rast, in_poly = my_poly)