elfdata: Retrieve and format data for ELF generation

In elfgen: Ecological Limit Function Model Generation and Analysis Toolkit

Retrieve and format data for ELF generation

Description

Given a HUC code, provides a dataframe of all contained nhdplus segments and their individual NT Total and Mean Annual Flow MAF values

Usage

elfdata(
  watershed.code,
  ichthy.localpath,
  use_cache = TRUE,
  update_cache = FALSE
)

Arguments

watershed.code	Hydrologic unit code, either HUC6, HUC8, HUC10, or HUC12 (e.g. HUC10 code '0208020101').
ichthy.localpath	Local file path for storing downloaded ichthy data. Defaults to a temp directory.
use_cache	Should the function look for a file with the same name in the file directory? This allows users to use the same Icthy dataset each time rather than needing to download separately when running multiple analyses
update_cache	Should the file be written out to use for future caching?

Value

A dataframe of nhdplus segments containing species richness data (NT Total values) and mean annual flow (MAF) data.

Examples

# We don't run this example by R CMD check, because it takes >10s

# Retrieve dataset of interest
# You may enter either a 6, 8, 10, or 12-digit HUC code.
# By default the ichthy dataset is downloaded to a temp directory, however this may be overridden by
# supplying a local path of interest using the input parameter 'ichthy.localpath'
watershed_df <- tryCatch({elfdata(watershed.code = '0208020104',
 ichthy.localpath = tempdir(), use_cache = FALSE)}, warning = function(w){print(w)},
 error = function(e){"internet resource error"})

elfgen documentation built on May 23, 2026, 9:10 a.m.