Question

当我尝试使用writeOGR和一个循环来保存我的shapefile时，除了给我一个错误信息之外它没有做任何事情：

writeOGR出错（plot.locationsSP_DROUGHT，dsn，layer1，driver =＆＃34; ESRI Shapefile＆＃34;）：图层存在，使用新的图层名称

基本上，我将每个对象转换为CSV文件，然后转换为shapefile，并希望同时保存CSV文件和shapefile。这是我的代码片段：

for (m in 1:500){
#First I want to save my CSV files:
drought.slice <- rotate(drought.array[m,,])
drought.vec <- as.vector(drought.slice)
length(drought.vec)
drought.df01 <- data.frame(cbind(lonlat, drought.vec))
names(drought.df01) <- c("lon", "lat", paste(dname, as.character(m), sep = "_"))
head(na.omit(drought.df01))
csvfile<-paste0("cru_drought_",m,".csv")

#Next I want to create shapefiles from the CSV files:
plot.locations_DROUGHT <- read.csv(paste0("cru_drought_",m,".csv"), stringsAsFactors = FALSE)
plot.locationsSP_DROUGHT <- SpatialPointsDataFrame(plot.locations_DROUGHT[,1:2], plot.locations_DROUGHT)
proj4string(plot.locationsSP_DROUGHT) <- CRS("+init=epsg:4326")
dsn <- layer1 <- gsub(".csv","cru_drought_",m)
writeOGR(plot.locationsSP_DROUGHT, dsn, layer1, driver="ESRI Shapefile")
}

以下是我使用的完整代码：

    #Open and read the NCDF file, along with longitude and latitude
rm(list=ls())
library(lattice)
library(ncdf4)
library(chron)
library(rgdal)
library(sp)
library(raster)
library(RColorBrewer)
setwd('/Users/Neil/Dropbox/Drought Maps')
ncname <- "owda-orig"
ncfname <- paste(ncname,".nc",sep="")
dname <- "pdsi"
ncin <- nc_open(ncfname)
print(ncin)

lon <- ncvar_get(ncin, "lon")
nlon <- dim(lon)
head(lon)

lat <- ncvar_get(ncin, "lat", verbose = F)
nlat <- dim(lat)
head(lat)

print(c(nlon, nlat))

t <- ncvar_get(ncin, "time")
nt <- dim(t)
head(t)

drought.array <- ncvar_get(ncin, dname)
dlname <- ncatt_get(ncin, dname, "long_name")
dunits <- ncatt_get(ncin, dname, "units")
#fillvalue <- ncatt_get(ncin, dname, "_FillValue")
dim(drought.array)

creation_date <- ncatt_get(ncin, 0, "creation_date")
Description <- ncatt_get(ncin, 0, "Description")

nc_close(ncin)



rotate <- function(x) t(apply(x, c(1, 2), rev))

m <- 333
drought.slice <- rotate(drought.array[m,,])
image(lon, lat, drought.slice, col = brewer.pal(10, "BrBG"))

lonlat <- expand.grid(lon, lat)
drought.vec <- as.vector(drought.slice)
length(drought.vec)

drought.df01 <- data.frame(cbind(lonlat, drought.vec))
names(drought.df01) <- c("lon", "lat", paste(dname, as.character(m), sep = "_"))
head(na.omit(drought.df01))


for (m in 1:500){
    drought.slice <- rotate(drought.array[m,,])
    drought.vec <- as.vector(drought.slice)
    length(drought.vec)
    drought.df01 <- data.frame(cbind(lonlat, drought.vec))
    names(drought.df01) <- c("lon", "lat", paste(dname,         as.character(m), sep = "_"))
    head(na.omit(drought.df01))
    csvfile<-paste0("cru_drought_",m,".csv")
    plot.locations_DROUGHT <- read.csv(paste0("cru_drought_",m,".csv"), stringsAsFactors = FALSE)
    plot.locationsSP_DROUGHT <- SpatialPointsDataFrame(plot.locations_DROUGHT[,1:2], plot.locations_DROUGHT)
    proj4string(plot.locationsSP_DROUGHT) <- CRS("+init=epsg:4326")
    dsn <- layer1 <- gsub(".csv","cru_drought_",m)
    writeOGR(plot.locationsSP_DROUGHT, dsn, layer1, driver="ESRI Shapefile")
}

非常感谢帮助。我可能做的事非常愚蠢。

Answer 1

我非常确定您的问题出在您创建shapefile名称的行中。使用gsub(".csv","cru_drought_",m)将取代＆＃34; .csv＆＃34;与＆＃34; cru_drought _＆＃34;在字符串m中，这只是您循环的整数。找不到该字符串，因此它只是将整数m分配给dsn，因此您最终会尝试编写名称为＆＃34; 1＆＃34;，＆＃34的shapefile ; 2＆＃34;等等。我认为你只有gsub个参数有点混乱。

我注释掉了代码中特定于您的文件的部分，并尝试将文件名放在一起，看起来就像您之后的那样。

for (m in 1:5){
    # drought.slice <- rotate(drought.array[m,,])
    # drought.vec <- as.vector(drought.slice)
    # length(drought.vec)
    # drought.df01 <- data.frame(cbind(lonlat, drought.vec))
    # names(drought.df01) <- c("lon", "lat", paste(dname,         as.character(m), sep = "_"))
    # head(na.omit(drought.df01))
    csvfile<-paste0("cru_drought_",m,".csv")
    # plot.locations_DROUGHT <- read.csv(paste0("cru_drought_",m,".csv"), stringsAsFactors = FALSE)
    # plot.locationsSP_DROUGHT <- SpatialPointsDataFrame(plot.locations_DROUGHT[,1:2], plot.locations_DROUGHT)
    # proj4string(plot.locationsSP_DROUGHT) <- CRS("+init=epsg:4326")
    dsn <- layer1 <- gsub(".csv","_shape",csvfile)
    # writeOGR(plot.locationsSP_DROUGHT, dsn, layer1, driver="ESRI Shapefile")
    print(dsn)
}
#> [1] "cru_drought_1_shape"
#> [1] "cru_drought_2_shape"
#> [1] "cru_drought_3_shape"
#> [1] "cru_drought_4_shape"
#> [1] "cru_drought_5_shape"

由reprex package（v0.2.0）创建于2018-04-14。

Answer 2

使用raster::shapefile而不是writeOGR

会更容易一些

shapefile(plot.locationsSP_DROUGHT, dsn)

R：循环以保存多个shapefile

2 个答案: