在专属经济区而不是国家边界上使用R中的coords2country函数

Question

我想将国家专属经济区分配给来自栅格的点数据，这些点表示海洋中的文石饱和度水平。光栅是为海洋中的许多纬度/经度点提供文石值的单个图层。我想将每个纬度/经度点分配给一个专属经济区。This site是针对单个坐标对的，但我有15,000个点，所以我希望它可以在R中实现。

数据如下所示：

      long      lat Aragonite
1 20.89833 84.66917  1.542071
2 22.69496 84.66917  1.538187
3 24.49159 84.66917  1.537830
4 26.28822 84.66917  1.534834
5 28.08485 84.66917  1.534595
6 29.88148 84.66917  1.532505

以前，我使用下面的代码将国家分配给栅格点，但这会为国家专属经济区内的海洋中的许多点返回NA。

#convert the raster to points for assigning countries
r.pts <- rasterToPoints(r, spatial = TRUE)

#view new proj 4 string of spatialpointsdataframe
proj4string(r.pts)
##[1] "+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0"

###converting reclassified points to countries
# The single argument to this function, points, is a data.frame in which:
#   - column 1 contains the longitude in degrees
#   - column 2 contains the latitude in degrees
coords2country = function(r.pts)
{
countriesSP <- getMap(resolution='high')
#countriesSP <- getMap(resolution='high') #you could use high res map from rworldxtra if you were concerned about detail

#setting CRS directly to that from rworldmap
r.pts = SpatialPoints(r.pts, proj4string=CRS(proj4string(countriesSP))) 

# use 'over' to get indices of the Polygons object containing each point 
indices = over(r.pts, countriesSP)
# return the ADMIN names of each country
indices$ADMIN 
#indices$ISO3 # returns the ISO3 code
#indices$continent   # returns the continent (6 continent model)
#indices$REGION   # returns the continent (7 continent model)
}

#get country names for each pair of points
rCountries <- coords2country(r.pts)

除了海洋中的专属经济区之外，有没有办法实现与coords2countries类似的功能？

编辑:可重现示例的一些数据

dput(head(r.pts))
structure(list(layer = c(5, 5, 5, 5, 5, 5), x = c(-178.311660375408,-176.511660375408, -174.711660375408, -172.911660375408, -171.111660375408,-169.311660375408), y = c(73.1088933113454, 73.1088933113454,73.1088933113454, 73.1088933113454, 73.1088933113454, 73.1088933113454),.Names = c("layer", "x", "y"),row.names = c(NA, 6L), class = "data.frame") 

Answer 1

您需要一个包含EEZ的shapefile。下载这里: World EEZ v9 (2016-10-21,123MB) http://www.marineregions.org/downloads.php#marbound

您可以使用rgdal包中的readOGR()函数加载EEZ shapefile。将EEZ shapefile压缩文件解压缩到您的工作目录中，然后运行countriesSP <- rgdal::readOGR(dsn = ".", layer = "eez_boundaries")代替countriesSP <- getMap(resolution='high')

您提供的示例数据都不在某个国家的专属经济区内，所以我不知道这是否真的有效，但它可能会……

library(sp)
library(rworldmap)
library(rgeos)

r <- read.table(header = TRUE, text = "
long lat Aragonite
1 20.89833 84.66917  1.542071
2 22.69496 84.66917  1.538187
3 24.49159 84.66917  1.537830
4 26.28822 84.66917  1.534834
5 28.08485 84.66917  1.534595
6 29.88148 84.66917  1.532505
")
# or
#r <- data.frame(long = c(-178.311660375408,-176.511660375408, -174.711660375408, -172.911660375408, -171.111660375408,-169.311660375408), 
#                lat = c(73.1088933113454, 73.1088933113454,73.1088933113454, 73.1088933113454, 73.1088933113454, 73.1088933113454))

r.pts <- sp::SpatialPoints(r)

# download file from here: http://www.marineregions.org/download_file.php?fn=v9_20161021
# put the zip file in your working directory: getwd()
unzip('World_EEZ_v9_20161021.zip')

# countriesSP <- rworldmap::getMap(resolution = "high")
# or
countriesSP <- rgdal::readOGR(dsn = ".", layer = "eez_boundaries")

r.pts <- sp::SpatialPoints(r.pts, proj4string = sp::CRS(proj4string(countriesSP))) 
indices <- over(r.pts, countriesSP)
indices$ADMIN