Question

我在ggplot2中使用fortify方法收到此错误：

Error in (function (classes, fdef, mtable) : unable to find an inherited method for function ‘proj4string’ for signature ‘"NULL"’

代码如下：

> library(maptools)
> gpclibPermit()
> library(ggplot2)
> library(rgdal)
> library(rgeos)
> library(ggmap)
> brMap <- readShapePoly("Google/BRASIL.shp")
> brMapDF <- fortify(brMap)
# This actually works

# But this don´t

> brMapDF <- fortify(brMap, region="UF")

Error in (function (classes, fdef, mtable)  : 
            unable to find an inherited method for function ‘proj4string’ for signature ‘"NULL"’

我的所有shapefile都会发生这种情况，所以我尝试了（在上面的代码中）我在stackoverflow Format the ggplot2 map中找到的shapefile，数据为https://docs.google.com/file/d/0B_coFit6AovfcEFkbHBjZEJaQ1E/edit

Answer 1

这是一种解决方法，但是如果您根据数据准备中的注释将UF列复制为id列，如示例wiki中所示，fortify的默认值将使用空间数据框中的第一列来分隔在id列下添加名称时相应地输出多边形。

library(maptools)
library(ggplot2)
library(sp)
library(rgdal)
library(rgeos)

brMap <- readShapePoly("Google/BRASIL", IDvar = "UF",
    proj4string = CRS("+init=epsg:4236"), repair = TRUE, verbose = TRUE)
brMap@data$id <- brMap@data$UF
brMapDF <- fortify(brMap)

brMapDF的结果是：

'data.frame':   9316 obs. of  7 variables:
 $ long : num  -68.6 -68.7 -68.8 -68.8 -68.9 ...
 $ lat  : num  -11.1 -11.2 -11.2 -11.1 -11.1 ...
 $ order: int  1 2 3 4 5 6 7 8 9 10 ...
 $ hole : logi  FALSE FALSE FALSE FALSE FALSE FALSE ...
 $ piece: Factor w/ 37 levels "1","2","3","4",..: 1 1 1 1 1 1 1 1 1 1 ...
 $ group: Factor w/ 81 levels "AC.1","AL.1",..: 1 1 1 1 1 1 1 1 1 1 ...
 $ id   : chr  "AC" "AC" "AC" "AC" ...

功能强化ggplot2时出错

1 个答案: