ecmwfr 1.4.0 CRAN release

We are happy to announce a new release of our ecmwfr R package, version 1.4.0. This new release comes with some exciting features thanks to a contribution by Elio Campitelli! Below you find a simple worked example on how to combine archetypes and batch requests to speed up data retrieval.

Batch query support example

As a pre-requisite you need to register for the ECMWF services and set your login key using the wf_set_key() function. Once done we can proceed.

# load the library
library(ecmwfr)

# set your CDS key
wf_set_key(
  user = "1111",
  key = "asfasdf-128242349-asdfasdf-asdfad",
  service = "cds"
  )

First, we will define an ‘archetype’, a function which allows you to manipulate certain fields in a data query. In this case we tag the area and day fields to be dynamic. As such, these fields can be changed dynamically using the newly created dynamic_request() function.

# this is an example of a request
# using an archetype
dynamic_request <- wf_archetype(
  request = list(
  "dataset_short_name" = "reanalysis-era5-pressure-levels",
  "product_type"   = "reanalysis",
  "variable"       = "temperature",
  "pressure_level" = "850",
  "year"           = "2000",
  "month"          = "04",
  "day"            = "04",
  "time"           = "00:00",
  "area"           = "70/-20/30/60",
  "format"         = "netcdf",
  "target"         = "era5-demo.nc"
  ),
  dynamic_fields = c("area","day"))

We use this new archetype to generate a list of two requests for two days. The new batch request function uses a list of requests during batch processing. These can be generated as shown or by substitution using a simple lapply() routine.

# creating a list of requests using wf_archetype()
# setting the day value dynamically
batch_request <- list(
  dynamic_request(day = "01"),
  dynamic_request(day = "02")
)

With this new list of requests we can use the wf_request_batch() function to request these datasets in parallel. Once the data is available a download is triggered and the data is downloaded to a desired location (with the default being temporary file storage).

# submit a batch job using 2 workers
# one for each in the list (the number of workers
# can't exceed 20)
wf_request_batch(
  batch_request,
  workers = 2,
  user = "1111"
  )