extract_data: Extract data

In epwshiftr: Create Future 'EnergyPlus' Weather Files using 'CMIP6' Data

Description

extract_data() takes an epw_cmip6_coord object generated using match_coord() and extracts CMIP6 data using the coordinates and years of interest specified.

Usage

extract_data(
  coord,
  years = NULL,
  unit = FALSE,
  out_dir = NULL,
  by = NULL,
  keep = is.null(out_dir),
  compress = 100
)

Arguments

coord	An epw_cmip6_coord object created using match_coord()
years	An integer vector indicating the target years to be included in the data file. All other years will be excluded. If NULL, no subsetting on years will be performed. Default: NULL.
unit	If TRUE, units will be added to values using units::set_units().
out_dir	The directory to save extracted data using fst::write_fst(). If NULL, all data will be kept in memory by default. Default: NULL.
by	A character vector of variable names used to split data during extraction. Should be a subset of: "experiment": root experiment identifiers "source": model identifiers "variable": variable identifiers "activity": activity identifiers "frequency": sampling frequency "variant": variant label "resolution": approximate horizontal resolution If NULL and out_dir is given, file name data.fst will be used. Default: NULL.
keep	Whether keep extracted data in memory. Default: TRUE if out_dir is NULL, and FALSE otherwise.
compress	A single integer in the range 0 to 100, indicating the amount of compression to use. Lower values mean larger file sizes. Default: 100.

Details

extract_data() uses future.apply underneath. You can use your preferable future backend to speed up data extraction in parallel. By default, extract_data() uses future::sequential backend, which runs things in sequential.

Value

An epw_cmip6_data object, which is basically a list of 3 elements:

• epw: An eplusr::Epw object whose longitude and latitute are used to extract CMIP6 data. It is the same object as created in match_coord()

• meta: A list containing basic meta data of input EPW, including city, state_province, country, latitute and longitude.

• data: An empty data.table::data.table() if keep is FALSE or a data.table::data.table() of 12 columns if keep is TRUE:

  No.	Column	Type	Description
  1	activity_drs	Character	Activity DRS (Data Reference Syntax)
  2	institution_id	Character	Institution identifier
  3	source_id	Character	Model identifier
  4	experiment_id	Character	Root experiment identifier
  5	member_id	Character	A compound construction from sub_experiment_id and variant_label
  6	table_id	Character	Table identifier
  7	lat	Double	Latitude of extracted location
  8	lon	Double	Latitude of extracted location
  9	variable	Character	Variable identifier
  10	description	Character	Variable long name
  11	units	Character	Units of variable
  12	value	Double	Start date and time of simulation

Examples

## Not run: 
coord <- match_coord("path_to_an_EPW")
extract_data(coord, years = 2030:2060)

## End(Not run)

epwshiftr documentation built on May 26, 2021, 5:08 p.m.