Download road emissions data — download

The download_nei() function accesses and downloads road emissions data from the U.S Environmental Protection Agency's (EPA) National Emissions Inventory (NEI).

Usage

download_nei(
  epa_certificate_path = system.file("extdata/cacert_gaftp_epa.pem", package = "amadeus"),
  certificate_url =
    "http://cacerts.digicert.com/DigiCertGlobalG2TLSRSASHA2562020CA1-1.crt",
  year = c(2017L, 2020L),
  directory_to_save = NULL,
  acknowledgement = FALSE,
  download = FALSE,
  remove_command = FALSE,
  unzip = TRUE,
  hash = FALSE
)

Arguments

epa_certificate_path: character(1). Path to the certificate file for EPA DataCommons. Default is 'extdata/cacert_gaftp_epa.pem' under the package installation path.
certificate_url: character(1). URL to certificate file. See notes for details.
year: integer(1) Available years of NEI data. Default is c(2017L, 2020L).
directory_to_save: character(1). Directory to save data. Two sub-directories will be created for the downloaded zip files ("/zip_files") and the unzipped data files ("/data_files").
acknowledgement: logical(1). By setting TRUE the user acknowledges that the data downloaded using this function may be very large and use lots of machine storage and memory.
download: logical(1). FALSE will generate a *.txt file containing all download commands. By setting TRUE the function will download all of the requested data files.
remove_command: logical(1). Remove (TRUE) or keep (FALSE) the text file containing download commands.
unzip: logical(1). Unzip the downloaded zip files. Default is FALSE.
hash: logical(1). By setting TRUE the function will return an rlang::hash_file() hash character corresponding to the downloaded files. Default is FALSE.

Value

For hash = FALSE, NULL
For hash = TRUE, an rlang::hash_file character.
Zip and/or data files will be downloaded and stored in respective sub-directories within directory_to_save.

Note

For EPA Data Commons certificate errors, follow the steps below:

Click Lock icon in the address bar at https://gaftp.epa.gov
Click Show Certificate
Access Details
Find URL with *.crt extension Currently we bundle the pre-downloaded crt and its PEM (which is accepted in wget command) file in ./inst/extdata. The instruction above is for certificate updates in the future.

References

United States Environmental Protection Agency (2024). “Air Emissions Inventories.” https://www.epa.gov/air-emissions-inventories.

Author

Ranadeep Daw, Insang Song

Examples

if (FALSE) { # \dontrun{
download_nei(
  year = c(2017L, 2020L),
  directory_to_save = tempdir(),
  acknowledgement = TRUE,
  download = FALSE, # NOTE: download skipped for examples,
  remove_command = TRUE,
  unzip = FALSE
)
} # }