融合是作为sf方法here讨论的常用地理处理技术。
我正在尝试复制融合，因为它在ArcGIS中的功能。考虑县两组在ArcGIS中。
ArcGIS融合命令将生成两个面，而不考虑东部半岛由其他单独的面组成的事实。

这是我想在sf中复制的功能，但是我不能，如下所示。

nc <- st_read(system.file("shape/nc.shp", package="sf"))

#create two homogenous spatial groups
nc$group <- ifelse(nc$CNTY_ <= 1980,1,2)

#plot
ggplot() + geom_sf(data=nc, aes(fill = factor(group)))  

#dissolve
library(dplyr)#the summarize function is based on the one from dplyr (which may interfere with summarize from other libraries that may be loaded)
nc_dissolve <- nc %>% group_by(group) %>% summarize() 

#plot dissolved
ggplot() + geom_sf(data=nc_dissolve, aes(fill = factor(group)))

#Cartographically, it looks like we have two polygons, but there are 
#actually several more wrapped up as MULTIPOLYGONS. We can plot these.
t <- nc_dissolve %>% st_cast() %>% st_cast("POLYGON")
ggplot() + geom_sf(data=t, aes(fill=factor(row.names(t))))

请注意，半岛具有多个无关的多边形。
我怎么能像ArcGIS那样只得到两个呢？非常感谢。