R 地图打印顶部的图层状态轮廓

我使用shapefile在R中根据某些条件创建地图文件。代码如下所示

   library('sp')
library('rgdal')
library('maptools')
gpclibPermit()
zip<-readShapePoly("C:/Users/Ishan.Basu/Desktop/shapefile/shapefile ZIP/USZ102.shp")
plot(zip)
ms2<-read.table("C:/Users/Ishan.Basu/Desktop/MS.txt",header=T,sep="\t",colClasses="character",as.is=T)

zip@data = merge(zip@data,ms2, by.x="ZIP", by.y="ZIP")

x<-zip@data
plot(zip,col=ifelse(zip@data$Seg=="Top Performers",'Dark Green',
                      ifelse(zip@data$Seg=="Average Performers",'Light Green',
                    ifelse(zip@data$Seg=="Poor Performers",'Yellow',
                           ifelse(zip@data$Seg=="Zero Returns",'Red',
                                  ifelse(zip@data$Seg=="Zero Activity",'Dark Red',
                                         'Grey'))))),
     border=ifelse(zip@data$Seg=="Top Performers",'Dark Green',
                   ifelse(zip@data$Seg=="Average Performers",'Light Green',
                          ifelse(zip@data$Seg=="Poor Performers",'Yellow',
                                 ifelse(zip@data$Seg=="Zero Returns",'Red',
                                        ifelse(zip@data$Seg=="Zero Activity",'Dark Red',
                                               'Grey'))))),
     bty="n")

现在我想要一种在形状文件上绘制状态轮廓的方法。 非常感谢您的快速回复

这对我来说很有用：

png(filename="D:\\analysis_f.png", width=2000, height=2000)
plot(zip,col=ifelse(zip@data$Seg=="Super Top",'Dark Green',
                      ifelse(zip@data$Seg=="Top Performer",'Light Green',
                    ifelse(zip@data$Seg=="Average Performer",'Yellow',
                           ifelse(zip@data$Seg=="Poor Performer",'Red',
                                  ifelse(zip@data$Seg=="Zero returns",'Dark Red',
                                         'Grey'))))),
     border=ifelse(zip@data$Seg=="Super Top",'Dark Green',
                   ifelse(zip@data$Seg=="Top Performer",'Light Green',
                          ifelse(zip@data$Seg=="Average Performer",'Yellow',
                                 ifelse(zip@data$Seg=="Poor Performer",'Red',
                                        ifelse(zip@data$Seg=="Zero returns",'Dark Red',
                                               'Grey'))))),
     bty="n")

map('state', plot = TRUE, fill = FALSE,add=TRUE)
dev.off()

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建议使用readOGR而不是readShapePoly来打开形状文件。我已经解决了所有问题，但我需要在顶部添加状态轮廓形状文件的投影是什么？