如何從 R 中的流統計 package 中提取分水嶺 shapefile？

Question

我有許多分水嶺（n = 116），我想提取 shapefile 以使用 R package streamstats 。 我了解它如何適用於單個分水嶺，但我希望有一個可以適用於我所有分水嶺的代碼，而不是單獨執行每個分水嶺。 我開發了一個類似於這個 SO question的代碼。 但是，我一直遇到我認為是 memory 限制問題，這導致代碼在編寫 shapefile 時拋出以下錯誤消息： ogrListLayers 中的錯誤（dsn = dsn）：無法打開數據源。

這是 memory 限制問題嗎？ 為什么代碼在編寫 shapefile 時遇到問題？

devtools::install_github("markwh/streamstats")
library(streamstats)
library(dplyr)
library(purrr)
library(tidyr)

setTimeout(9999)

### Example data, seems like a lot but needed to demonstrate issue

dat1 <- data.frame(matrix(ncol = 3, nrow = 5))
x <- c("state","lat","long")
colnames(dat1) <- x
dat1$state <- c("VA","NC","NC","SC","SC")
dat1$lat <- c(38.06957, 36.39778, 36.52250, 33.83295, 33.64908)
dat1$long <- c(-79.89700, -79.19667, -78.99750, -79.04365, -79.09347)

water_shed <- list()

### Hits the StreamStats API (https://streamstats.usgs.gov/docs/streamstatsservices/#/)
### and delineates the watersheds. This can handle all the 100+ watersheds

for(i in 1:nrow(dat1)){
  water_shed[[i]] <- 
    delineateWatershed(xlocation = dat1$long[i], ylocation = dat1$lat[i], crs = 4326,
                       includeparameters = "false",
                       includeflowtypes = "false",
                       includefeatures = "true",
                       rcode = dat1$state[i])
}

### Writes the shapefiles into my directory
### This is when the error message gets thrown

for(i in 1:length(water_shed)){
  writeShapefile(watershed = water_shed[[i]],
                 layer = water_shed[[i]],
                 dir = ".",
                 what = "boundary")
  
}

Answer 1

使用tryCatch處理運行時錯誤

for(i in 1:nrow(dat1)){
    water_shed[[i]] <- 
      tryCatch({delineateWatershed(xlocation = dat1$long[i], 
              ylocation = dat1$lat[i], crs = 4326,
                         includeparameters = "false",
                         includeflowtypes = "false",
                         includefeatures = "true",
                         rcode = dat1$state[i])},
                         
                         error = function(e) e)
                         
                         
  }

將文件寫入目錄

for(i in seq_along(water_shed)){
   writeShapefile(watershed = water_shed[[i]],
                  layer = water_shed[[i]],
                  dir = "shapefile_tmp",
                  what = "boundary")
  
 }

-檢查 output 目錄