[R] Match coordinates to regional polygon

[Bert Gunter]

I believe this would be better posted on r-sig-Geo  .

Bert Gunter

"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )


On Mon, Mar 9, 2020 at 3:16 PM Miluji Sb <milujisb using gmail.com> wrote:

> Dear all,
>
> I am trying to match a large number of coordinates (attached) sub-national
> regions using GADM shapefile.
>
> Coordinates:
>
> https://drive.google.com/file/d/1PUsi4d0wP7hB6Aps6UmpXsnIPSD3I1sT/view?usp=sharing
>
> Shapefile:
>
> https://drive.google.com/drive/folders/1DxyygjQNeg2GIS9doaFM8yM2LvBYZi8E?usp=sharing
>
>
> This is the code I am using;
>
> ###
> library(data.table)
> library(ncdf4)
> library(rgdal)
> library(raster)
> library(tidyverse)
>
> ## Read coordinates
> coords <- read.csv("coords.csv")
>
> ## Read shapefile
> world <-readOGR(dsn = "/gadm36_levels_shp", layer = "gadm36_2")
>
> ## Convert to spatial points
> pts <- coords
> coordinates(pts) <- ~lon+lat
>
> ## Provide the same CRS to the coordinates as the shapefile
> proj4string(pts) <- proj4string(world)
>
> ## Use over function to match coordinates to polygons
> pts_district <- over(pts, world)$NAME_1
> ###
>
> However, less than 20% of the coordinates are matched to a polygon. What am
> I doing wrong? Any help will be greatly appreciated.
>
> Regards,
>
> Milu
>
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>
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