elfgen (version 2.3.4)

bkpt_pwit: Identify breakpoint location with PWIT

Description

This applies the Piecewise Iterative elfgen method. This approach uses an iterative algorithm to identify shifts in the relation between maximum richness and stream size. A user specifies a "quantile" for isolating an upper subset of the data. A user also identifies a bounding range between two x-values ("blo" = "bound low", "bhi" = "bound high") in which the upper subest of data is believed to contain a breakpoint. (Note: Small datasets may not contain a breakpoint)

Usage

bkpt_pwit(watershed.df, quantile, blo, bhi)

Value

Breakpoint value is returned

Arguments

watershed.df

A dataframe of sites with ecological and hydrologic data

quantile

Specified value for the quantile of interest - 0.95 refers to the 95th percentile

blo

A "bound low" value, or the lower bound of the piecewise range

bhi

A "bound high" value, or the upper bound of the piecewise range

Details

See: Lemoine, N. 2012. "R for Ecologists: Putting Together a Piecewise Regression." https://www.r-bloggers.com/r-for-ecologists-putting-together-a-piecewise-regression/ The R Book, Second Edition. Michael J. Crawley. 2013 John Wiley & Sons, Ltd. Published 2013 by John Wiley & Sons, Ltd.

Examples

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

watershed.df <- elfdata(watershed.code = '0208020104',
 ichthy.localpath = tempdir(), use_cache = FALSE)
bkpt_pwit(watershed.df,0.85,100,300)
# }