R - 槽不可达？ [英] R - Slot unreachable?

问题描述

当我试图添加地理参考的tif文件到我的ggplots在R，我遇到一个看似奇怪的插槽问题：使用 raster（）我无法到达 colortable -slot：

As I am trying to add georeferenced tif-files to my ggplots in R, I have encountered a seemingly weird problem with slots: After loading the raster file using raster() I can't reach its colortable-slot:

>>获取示例tif文件<<< ： p>

>>Grab the example tif-file<<:

raster1 <- raster(paste(workingDir, "/HUEK200_Durchlaessigkeit001_proj001.tif", sep="", collapse=""))
raster1@colortable  #or
slot(raster1, "colortable")

最后两行显示同样的错误信息：

The two last lines shoudl work equally but result both in the error message:

Error in slot(raster1, "colortable") : 
  no slot of name "colortable" for this object of class "RasterLayer"

混淆，因为通过属性（raster1）很清楚地列出了属性：

This is confusing because a small glimpse into the attributes via attributes(raster1) clearly lists exactly that slot:

Slot "colortable":
  [1] "#FFFFFF" "#000000" "#B49ED7" "#9B7DCF" "#9EAAD7" "#B2BEEB" "#B4EBB4"
  [8] "#F5E1B5" "#CCB792" "#B9A08C" "#0070FF" "#0000C8" "#F8F8F8" "#DBF5FF"
 [15] "#B14D00" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [22] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [29] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [36] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [43] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [50] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [57] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [64] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [71] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [78] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [85] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [92] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
 [99] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[106] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[113] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[120] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[127] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[134] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[141] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[148] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[155] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[162] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[169] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[176] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[183] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[190] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[197] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[204] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[211] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[218] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[225] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[232] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[239] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[246] "#000000" "#000000" "#000000" "#000000" "#000000" "#000000" "#000000"
[253] "#000000" "#000000" "#000000" "#000000"

是我是谁在做错事在第一个地方，还是它是一个错误？如何才能终于访问colortable？我知道从调用 plot（raster1）它应该工作，因为情节显示正确的颜色集。此外：通常，在管理空间多边形对象时， S4object @ someslot -approach对我来说很好。

Is it me who is doing something wrong in the first place or could it be a bug? And how can I finally access the colortable? I know from calling plot(raster1) that it should work because the plot displays the correct color-set. Furthermore: Normally, the S4object@someslot-approach works just fine for me when managing spatial polygon objects.

：
当属性（raster1）尝试访问其他插槽列表时，在 colortable

Beside colortable the same error appears when trying to access other slots listes by attributes(raster1).

感谢您的帮助！

推荐答案

我现在。我只是误读从属性（raster1）的（不完全明显）输出。 colortable -slot不是直接（第一顺序）光栅对象接口的一部分，如果你可以调用它在R中。列在 legend 如下：

I have found the answer myself now. I simply misread the (not completely obvious) output from attributes(raster1). The colortable-slot is not part of the direct (first order) raster-object-interface, if you can call it liek that in R. Rather it is listed in the legend like so:

attr(raster1, "legend")@colortable

R中的引用总是会让我感到惊讶！ ：）

References in R always tend to surprise me! :)

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