自行编写的软件包:spatialPolygonsDataFrame的载荷图方法 [英] Self-authored package: load plot method for spatialPolygonsDataFrame

问题描述

我正在编写自己的R包，并希望绘制一个spatialPolygonsDataFrame对象.如果我将其编写为脚本，则只需使用library()加载必要的程序包(maptools，rgdal和rgeos)，并使用plot(x)进行绘图.

I'm writing my own R package and would like to plot a spatialPolygonsDataFrame object. If I were writing it as a script I would simply load the necessary packages (maptools, rgdal, and rgeos) with library() and plot with plot(x).

在编写使用library()构建的软件包时，不建议使用 ，通常是通过将软件包添加到NAMESPACE中的Imports:来加载软件包.如果执行此操作，则会收到以下错误:

When writing a package to build using library() is not advised, instead it is usual to load the package by adding it to Imports: in the NAMESPACE. If I do this I receive the following error:

as.double(y)中的错误: 无法将类型"S4"强制转换为类型"double"的向量

Error in as.double(y) : cannot coerce type 'S4' to vector of type 'double'

这是在编写脚本时通过将maptools程序包与library()一起加载进行了更正.

This is is corrected by loading the maptools package with library() if writing a script.

我知道您可以在NAMESPACE中的ImportMethodsFrom中加载单个方法，因此尝试使用此方法从maptools导入绘图方法，但是没有运气.当我查看maptools包的NAMESPACE时，找不到导出的plot方法.我已经看到有一个plot.Spatial函数，我试图将其导入到我的NAMESPACE中却没有成功:

I know you can load individual methods with ImportMethodsFrom in the NAMESPACE so have tried to import a plot method from maptools using this approach but have had no luck. When I looked in the NAMESPACE of the maptools package I couldn't find a plot method exported. I've seen there is a plot.Spatial function which I have tried to import to my NAMESPACE without success:

在"maptools"中找不到请求的方法:plot.Spatial

No methods found in "maptools" for requests: plot.Spatial

最后，我尝试在我的NAMESPACE中将maptools添加到Depends:而不是Imports:，这确实可行.这是做到这一点的规范方法吗?为一种方法附加整个程序包似乎有些矫kill过正(另外，我不知道已屏蔽了哪些功能，等等).加载必要的工具以在自定义函数中绘制地图的最佳方法是什么?

Finally, I have tried adding maptools to Depends: instead of Imports: in my NAMESPACE and this does work. Is this the canonical way to do this? It seems overkill to attach a whole package for one method (plus I don't know what functions have been masked, etc.). What is the best way to load the necessary tools to plot maps within a self-authored function?

针对@ Hack-R的问题，我不知道是否plot.Spatial是我唯一需要的方法，即使它是正确的方法.据我所知，这将使我能够绘制spatial对象.

Edit 1: In response to @Hack-R's question, I don't know if plot.Spatial is the only method I need, or even if it's the correct one. It's my educated guess that this will enable me to plot spatial objects.

推荐答案

@mdsumner的回答为我指明了正确的方向，并且就其本身而言是有益的讨论.

@mdsumner's answer pointed me in the right direction and was a useful discussion in its own right.

我对绘制spatialPolygonsDataFrame对象的特定查询的答案是将sp添加到Imports:并调用sp::plot()

The answer to my specific query to plot spatialPolygonsDataFrame objects was to add sp to Imports: and call sp::plot()

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