Question

我试图使用以下代码更改县名正确命名，即alcona，而不是michigan,alcona。

michigan.map <- map("county", 'michigan',plot=FALSE, fill = TRUE)
michigan.map$names
IDs <- sapply(strsplit(michigan.map$names, ":"), function(x) x[1])
michigan.sp <- map2SpatialPolygons(michigan.map, IDs = IDs,
                            proj4string = CRS("+proj=longlat +ellps=WGS84"))
plot(michigan.sp)
names(michigan.sp)
names(michigan.sp) <- sapply(strsplit(names(michigan.sp), ","), function(x) x[2])

它给了我：

“名称错误（michigan.sp）＆lt; - sapply（strsplit（names（michigan.sp），”，“）,: class'SpiftialPolygons'没有'名字'插槽“。

我不确定为什么因为它有名字槽。

另外作为一个附带问题，ID行在代码中做了什么？

Answer 1

我的评论显示了如何解决您正在做的事情，但为什么不进一步使用更现代/准确的县界？

library(sp)
library(rgdal)
library(tigris) #devtools::install_github("walkerke/tigris")

mi <- counties("michigan", detailed=FALSE)
head(mi@data)
##     STATEFP COUNTYFP COUNTYNS       AFFGEOID GEOID         NAME LSAD      ALAND     AWATER
## 141      26      041 01622963 0500000US26041 26041        Delta   06 3033127269 2124385360
## 142      26      047 01622966 0500000US26047 26047        Emmet   06 1210886745 1073476051
## 143      26      097 01622991 0500000US26097 26097     Mackinac   06 2646869250 2793795315
## 144      26      141 01623013 0500000US26141 26141 Presque Isle   06 1706067776 4957327559
## 145      26      153 01623017 0500000US26153 26153  Schoolcraft   06 3033812509 1845664188
## 146      26      163 01623022 0500000US26163 26163        Wayne   06 1585109570  157120883

plot(mi)

Answer 2

michigan.map <- map("county", 'michigan',plot=FALSE, fill = TRUE)
IDs <- sapply(strsplit(michigan.map$names, ","), function(x) x[2])
michigan.sp <- map2SpatialPolygons(michigan.map, IDs = IDs,
                                   proj4string = CRS("+proj=longlat +ellps=WGS84"))
names(michigan.sp)

我认为这段代码符合你的要求......它并没有完全回答你的问题。必须有一种方法可以在创建后设置sp对象的ID，但名称＆lt; - 不是它。

Answer 3

str(michigan.sp)是你的朋友;滚动查看结果，您会看到确实没有插槽names。至少对我来说，更容易和更清楚的是改变michigan.map

michigan.map$names <- gsub('michigan,' ,'', michigan.map$names)
michigan.map$names
 [1] "alcona"         "alger"          "allegan"        "alpena"         "antrim"        
 [6] "arenac"         "baraga"         "barry"          "bay"            "benzie"        
[11] "berrien"        "branch"         "calhoun"        "cass"           "charlevoi"     
[16] "cheboygan"      "chippewa"       "clare"          "clinton"        "crawford"      
[21] "delta"          "dickinson"      "eaton"          "emmet"          "genesee"       
[26] "gladwin"        "gogebic"        "grand traverse" "gratiot"        "hillsdale"     
[31] "houghton"       "huron"          "ingham"         "ionia"          "iosco"         
[36] "iron"           "isabella"       "jackson"        "kalamazoo"      "kalkaska"      
[41] "kent"           "keweenaw"       "lake"           "lapeer"         "leelanau"      
[46] "lenawee"        "livingston"     "luce"           "mackinac"       "macomb"        
[51] "manistee"       "marquette"      "mason"          "mecosta"        "menominee"     
[56] "midland"        "missaukee"      "monroe"         "montcalm"       "montmorency"   
[61] "muskegon"       "newaygo"        "oakland"        "oceana"         "ogemaw"        
[66] "ontonagon"      "osceola"        "oscoda"         "otsego"         "ottawa"        
[71] "presque isle"   "roscommon"      "saginaw"        "st clair"       "st joseph"     
[76] "sanilac"        "schoolcraft"    "shiawassee"     "tuscola"        "van buren"     
[81] "washtenaw"      "wayne"          "weford"

类'SpatialPolygons'没有'名称'插槽

3 个答案: