使用ggplot2绘制sf多边形，使用变量绘制颜色

Question

我很习惯ggplot2，但没有那么多sf。我已经使用st_as_sf（）将spatialpolygonsdataframe转换为sf，现在我正在尝试绘制它。为什么我的变量'test'是一个矩阵？我做错了什么？

class(wards)
[1] "sf"         "data.frame"

names(wards)
 [1] "wd16cd"                  "wd16nm"                  "lad16nm"                
 [4] "test"                    "2015_no2_total"          "2020_no2_total"         
 [7] "2025_no2_total"          "2030_no2_total"          "2011_pm25_total"        
 [10] "2011_pm25_secondary"     "2011_pm25_residual_salt" "2015_pm25_total"        
 [13] "2015_pm25_secondary"     "2015_pm25_residual_salt" "2020_pm25_total"        
 [16] "2020_pm25_secondary"     "2020_pm25_residual_salt" "2025_pm25_total"        
 [19] "2025_pm25_secondary"     "2025_pm25_residual_salt" "2030_pm25_total"        
 [22] "2030_pm25_secondary"     "2030_pm25_residual_salt" "geometry"               

 class(wards$test)
 [1] "matrix"

 ggplot(wards) +
 +   geom_sf(aes(fill = test))

 Error: Column `fill` must be a 1d atomic vector or a list

谢谢，詹姆斯