CODEWITHSUNDEEP
rgis
maximusdooku
maximusdooku

Reputation: 5542

How can I download GADM data in R?

library(raster)   
france<-getData('GADM', country='FRA', level=1)

However, the command is leading me to this error.

trying URL 'http://biogeo.ucdavis.edu/data/gadm2.8/rds/FRA_adm1.rds'
Error in utils::download.file(url = aurl, destfile = fn, method = "auto",  : 
  cannot open URL 'http://biogeo.ucdavis.edu/data/gadm2.8/rds/FRA_adm1.rds'

Upvotes: 8

Views: 5881

Answers (2)

strboul
strboul

Reputation: 400

First, download the country data you want from the GADM database, and save it to your local directory. Be sure that you have chosen the R (SpatialPolygonsDataFrame) format. There are five levels available for France (from level 0 to level 5). You can choose what you need.

Second, read the .rds file downloaded from GADM with readRDS() function and transform it into a data.frame with ggplot2::fortify().

library(ggplot2)
library(sp)
# assumed that you downloaded into a such path: '~/Downloads/FRA_adm1.rds':
path <- file.path(Sys.getenv("HOME"), "Downloads", "FRA_adm1.rds")
# FR map (Level 1) from GADM version 2.8
frRDS <- readRDS(path)
# Region names 1 in data frame
frRDS_df <- ggplot2::fortify(frRDS, region = "NAME_1")
head(frRDS_df)

Upvotes: 7

Gray
Gray

Reputation: 1398

I am going to improve upon the previous answer to the OP's question.

To answer the OP's question directly and correctly, there is nothing wrong with the OP's code. The issue was likely a temporary internet connection issue because the OP's code works and retrieves the gadm.org data without issue. Note, the getData() function retrieves the gadm.org website's geodata that is stored and retrieved from the http://biogeo.ucdavis.edu/ website.

The raster package provides the getData() function which is very useful for automatically retrieving the geodata from the internet. This function can also be used to retrieve geodata that is kept locally on a PC.

In years past, the way to use geodata was to first download a file from the gadm.org website, and then to move that file from the download folder and save the file in a folder on the pc. These files then needed to be unpackaged/unzipped before the geodata was available to be used by R.

Using the getData() makes life simpler because this method directly retrieves the desired geodata and then makes the geodata available to use with R.

The gadm.org website clearly states:

"Downloading by country is the recommended approach"

Even though downloading the large world geodata file directly from the website can be done, it is unnecessary and resource intensive. Unless there is some specific reason for doing so, there is absolutely no need to download and keep the large worldwide geodata database on the PC.

And one last thing about the getData() function. This function is currently generating a warning when it is used in R nowadays. The warning reads:

Warning message in getData("GADM", country = "USA", level = 1):
"getData will be removed in a future version of raster.
Please use the geodata package instead"

Upvotes: 1

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