Build the URL(s) of the data to download

This is the main function of the package. It enables to build the URL(s) of the spatiotemporal datacube to download, given a collection, variables, region and time range of interest.

grd_get_url(collection, variables = NULL, roi = NULL,
  time_range = NULL, credentials = NULL)

Arguments

collection	string. mandatory. Collection of interest (see details).
variables	string vector. optional. Variables to retrieve for the collection of interest. If not specified (default) all available variables will be extracted (see details).
roi	object of class sf or sfc. mandatory. Region of interest. Must be POLYGON-type geometry composed of one single feature.
time_range	date(s) / POSIXlt of interest . mandatory. Single date/datetime or time frame : vector with start and end dates/times (see details).
credentials	vector string of length 2 with username and password. optional.

Value

a data.frame with one row for each dataset to download and 4 columns :

time_start

Start Date/time for the dataset

name

Indicative name for the dataset

url

http URL of the dataset

destfile

Indicative destination file for the dataset

Details

Argument collection : Collections available can be retrieved with the function grd_list_collections

Argument variables : For each collection, variables available can be retrieved with the function grd_list_variables

Argument time_range : Can be provided either as i) a single date (e.g. as.Date("2017-01-01")) or ii) a time frame provided as two bounding dates (starting and ending time) ( e.g. as.Date(c("2010-01-01","2010-01-30"))) or iii) a POSIXlt single time (e.g. as.POSIXlt("2010-01-01 18:00:00")) or iv) a POSIXlt time range (e.g. as.POSIXlt(c("2010-01-01 18:00:00","2010-01-02 09:00:00"))) for the half-hourly collection (GPM_3IMERGHH.06). If POSIXlt, times must be in UTC.

Examples

# NOT RUN {
require(sf)

roi = st_as_sf(data.frame(
geom = "POLYGON ((-5.82 9.54, -5.42 9.55, -5.41 8.84, -5.81 8.84, -5.82 9.54))"),
wkt = "geom",crs = 4326)

time_range = as.Date(c("2017-01-01","2017-01-30"))

# SRTM
(strm_urls <- grd_get_url(collection = "SRTMGL1.003", roi = roi))

# TAMSAT
(tamsat_urls <- grd_get_url(collection = "TAMSAT",variables = c("daily_rainfall_estimate","monthly_rainfall_estimate","monthly_anomaly"), time_range = time_range))

# VIIRS_DNB_MONTH
(viirsdnb_urls <- grd_get_url(collection = "VIIRS_DNB_MONTH",variables = c("Monthly_AvgRadiance","Monthly_CloudFreeCoverage"), roi = roi, time_range = time_range))

# MIRIADE
(imcce_urls <- grd_get_url(collection = "MIRIADE", roi = roi, time_range = time_range))

# ERA5
(era5_urls <- grd_get_url(collection = "ERA5", variables = c("10m_u_component_of_wind","10m_v_component_of_wind"), roi = roi, time_range = time_range))
# }