oce (version 1.0-1)

sectionSmooth: Smooth a Section

Description

Smooth a section in the lateral (alpha version that may change).

Usage

sectionSmooth(section, method = c("spline", "barnes"), xg, yg, xgl, ygl,
  xr, yr, gamma = 0.5, iterations = 2, trim = 0, pregrid = FALSE,
  debug = getOption("oceDebug"), ...)

Arguments

section

A section object containing the section to be smoothed. For method="spline", the pressure levels must match for each station in the section.

method

Specifies the method to use; see ‘Details’.

xg, xgl

passed to interpBarnes, if method="barnes"; ignored otherwise. If xg is supplied, it defines the x component of the grid, i.e. the resultant "stations". Alternatively, if xgl is supplied, the x grid is established using seq, to span the data with xgl elements. If neither of these is supplied, the output x grid will equal the input x grid.

yg, ygl

similar to xg and xgl.

xr, yr

influence ranges in x and y, passed to interpBarnes if method="barnes"; ignored otherwise.

gamma

scale-reduction parameter, passed to interpBarnes, if method="barnes"; ignored otherwise.

iterations

number of iterations of Barnes algorithm, passed to interpBarnes, if method="barnes"; ignored otherwise.

trim

passed to interpBarnes, if method="barnes"; ignored otherwise

pregrid

passed to interpBarnes, if method="barnes"; ignored otherwise

debug

A flag that turns on debugging. Set to 1 to get a moderate amount of debugging information, or to 2 to get more.

...

Optional extra arguments, passed to either smooth.spline or interpBarnes.

Value

An object of section-class that ordered in some way.

Details

This function should be used with caution, as should any operation that changes data. Although smoothing may be desirable to produce aesthetically-pleasing plots, it can also introduce artifacts that can lead to erroneous conclusions. The prudent analyst starts by comparing plots of the raw data with plots of the smoothed data.

For method="spline", the section is smoothed using smooth.spline on individual pressure levels, with any parameters listed in parameters being passed to that function. If df is not present in parameters, then this function sets it to the number of stations divided by 5. Smoothing is done separately for temperature, salinity, and sigma-theta.

For the (much slower) method="barnes" method, smoothing is done across both horizontal and vertical coordinates, using interpBarnes. The stations are changed to lie on the grid supplied defined xg and yg, or by xgl and ygl (see those arguments)

See Also

Other things related to section data: [[,section-method, [[<-,section-method, as.section, handleFlags,section-method, initializeFlagScheme,section-method, plot,section-method, read.section, section-class, sectionAddStation, sectionGrid, sectionSort, section, subset,section-method, summary,section-method

Examples

# NOT RUN {
library(oce)
data(section)
gs <- subset(section, 109<=stationId&stationId<=129)
gsg <- sectionGrid(gs, p=seq(0, 5000, 150))
gss1 <- sectionSmooth(gsg, "spline", df=16)
plot(gss1)
# }
# NOT RUN {
gss2 <- sectionSmooth(gsg, "barnes", xr=24, yr=100)
plot(gss2)
# }
# NOT RUN {
# }