getwts: Get weights for regression

In WRTDStidal: Weighted Regression for Water Quality Evaluation in Tidal Waters

Get weights for regression

Description

Get weights for WRTDS for a single observation using a tri-cubic weighting function

Usage

getwts(dat_in, ...)

## Default S3 method:
getwts(
  dat_in,
  ref_in,
  wt_vars = c("day_num", "dec_time", "flo"),
  wins = list(0.5, 10, NULL),
  all = FALSE,
  slice = TRUE,
  ngrzero = FALSE,
  wins_only = FALSE,
  min_obs = 100,
  ...
)

Arguments

dat_in	input tidal object
...	arguments passed to or from other methods
ref_in	row of tidal object as reference for weights
wt_vars	chr string of three elements indicating names of columns in tidal object that are used for reference row weights
wins	list of half-window widths for time, year, and flow
all	logical to return individual weights rather than the product of all three, default FALSE
slice	logical indicating if data are subset by observations within the maximum window width for faster calculations
ngrzero	logical indicating if count of observations with weights greater than zero is returned
wins_only	logical if the half-window widths should be returned as a list
min_obs	numeric vector for window widening if the number of observations with non-zero weights is less than the specified value, use min_obs = NULL to suppress this behavior

Details

The default half-window widths for day_num, year, and flow are half a day (12 hours), 10 years, and half the range of salinity/flow in the input data. The half-window widths are expanded by 10% until at least 100 observations have weights greater than zero. This behavior can be suppressed by setting min_obs = NULL.

Value

A vector of weights with length equal to the number of observations (rows) in the tidal object. Vectors for all three weighting variables are returned if all = TRUE.

Examples

##
data(tidobj)

# get weights for first row
first <- tidobj[1, ]
wts <- getwts(tidobj, first)

plot(wts, type = 'l')

## Not run: 

# get count of observations with grzero weights
sapply(1:nrow(tidobj), function(row) getwts(tidobj, tidobj[row, ], 
 ngrzero = TRUE))

## End(Not run)

WRTDStidal documentation built on Oct. 20, 2023, 5:08 p.m.