问题描述
我有一个以值作为因子的栅格图层和一个属性表。我想将其转换为SpatialPixelsDataFrame,但是当我尝试:
library(sp)
library(sf)
library(rgdal)
library(raster)
library(FedData)
library(rasterVis)
create_factor_rast <- function(base_rast,Spatial_polygon,fieldname) {
nam <- unique(Spatial_polygon[[fieldname]])
nam_df <- data.frame(ID = 1:length(nam),nam = nam)
idfieldname = paste0(fieldname,"ID")
Spatial_polygon[[idfieldname]] <- nam_df$ID[match(Spatial_polygon[[fieldname]],nam_df$nam)]
new_raster <- rasterize(x=Spatial_polygon,y=base_rast,field = idfieldname)
new_raster <- ratify(new_raster)
# # Create levels
rat <- levels(new_raster)[[1]]
rat$names <- nam_df$nam
rat$IDs <- nam_df$ID
levels(new_raster) <- rat
new_raster
}
spft <- "+proj=lcc +lat_1=40 +lat_2=43 +lat_0=39.83333333333334 +lon_0=-100 +x_0=500000.0000000002 +y_0=0 +datum=NAD83 +units=us-ft +no_defs"
SSURGO.dl <- FedData::get_ssurgo(template=c('NE043'),label = "Tau",raw.dir = "./SSURGO_r/RAW/SSURGO",extraction.dir = paste0("./SSURGO_R/EXTRACTIONS/","soils","/SSURGO"))
SSURGO.dl_shp<-SSURGO.dl$spatial
unlink('SSURGO_r',recursive=TRUE)
# extract the muaggatt table
muaggatt<-SSURGO.dl[["tabular"]][["muaggatt"]]
# get only the fields needed,must have mukey to do the join
muaggatt <- muaggatt[c("mukey","hydgrpdcd","drclassdcd")]
SSURGO_merge <- merge(SSURGO.dl_shp,muaggatt,by.x = "MUKEY",by.y="mukey")
# Convert merged SSURGO polygon to Stateplane feet
SSURGO_merge <- sf::st_transform(SSURGO_merge,crs(spft))
SSURGO_merge <- as(SSURGO_merge,"Spatial")
grid_cell_size <- 100 # ~30 meters
shp_extent <- extent(SSURGO_merge)
r <- raster(SSURGO_merge,resolution = grid_cell_size,crs=crs(SSURGO_merge))
r.drclassdcd <- create_factor_rast(r,SSURGO_merge,'drclassdcd')
rasterVis::levelplot(r.drclassdcd)
r.drclassdcd_sp <- as(r.drclassdcd,"SpatialPixelsDataFrame")
最后一行给出以下错误:
h(simpleError(msg,call))中的错误: 选择函数'as.factor'的方法时评估参数'x'时出错:未定义的列已选择
是否有一种方法可以从栅格图层获取像素数据帧,并将因子转换回属性字段中的字符?
解决方法
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