Question

我想指定国家专属经济区来指向来自栅格的数据，其中点代表海洋中的文石饱和度。栅格是单层，为海洋中的许多纬度/经度点提供Aragonite值。我想将每个纬度/经度点分配到专属经济区。 This site为单对坐标做了它，但我有15,000点，所以我希望可以用R做。

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/地区分配给光栅点，但这样可以为国家专属经济区内的海洋中的许多点提供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)

有没有办法对coords2countries执行类似的功能，但对于海洋中的EEZ呢？

编辑：一些数据可重现的例子

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

您需要包含EEZ的shapefile。下载这里的一个：World EEZ v9（2016-10-21,123 MB）http://www.marineregions.org/downloads.php#marbound

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

您提供的示例数据都不属于某个国家/地区的专属经济区，因此我无法判断这是否真的有效，但可能应该...

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

在专属经济区而非国家边界的R中使用coords2country功能

1 个答案: