R: Grid a Section

sectionGrid {oce} | R Documentation

## Grid a Section

### Description

Grid a section, by interpolating to fixed pressure levels. The `"approx"`, `"boxcar"` and `"lm"` methods are described in the documentation for `ctdDecimate`, which is used to do this processing. The default `"approx"` method is best for bottle data, the `"boxcar"` is best for ctd data, and the `"lm"` method is probably too slow to recommend for exploratory work, in which it is common to do trials with a variety of `"p"` values.

### Usage

    sectionGrid(section, p, method = "approx",
      debug = getOption("oceDebug"), ...)

### Arguments

`section` | A `section` object containing the section to be gridded.
`p` | Optional indication of the pressure levels to which interpolation should be done. If this is not supplied, the pressure levels will be calculated based on the typical spacing in the ctd profiles stored within `section`. If `p="levitus"`, then pressures will be set to be those of the Levitus atlas, given by `standardDepths`, trimmed to the maximum pressure in `section`. If `p` is a single numerical value, it is taken as the number of subdivisions to use in a call to `seq` that has range from 0 to the maximum pressure in `section`. Finally, if a vector numerical values is provided, then it is used as is.
`method` | The method to use to decimate data within the stations; see `ctdDecimate`, which is used for the decimation.
`debug` | an integer specifying whether debugging information is to be printed during the processing. This is a general parameter that is used by many `oce` functions. Generally, setting `debug=0` turns off the printing, while higher values suggest that more information be printed. If one function calls another, it usually reduces the value of `debug` first, so that a user can often obtain deeper debugging by specifying higher `debug` values.
`...` | Optional arguments to be supplied to `ctdDecimate`, e.g. `rule` controls extrapolation beyond the observed pressure range, in the case where `method` equals `"approx"`.

### Value

An object of `section-class` that contains stations whose pressure values match identically.

### A note about flags

Data-quality flags contained within the original object are ignored by this function, and the returned value contains no such flags. This is because such flags represent an assessment of the original data, not of quantities derived from those data. This function produces a warning to this effect. The recommended practice is to use `handleFlags` or some other means to deal with flags before calling the present function.

### Author(s)

Dan Kelley

### 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`, `sectionSmooth`, `sectionSort`, `section`, `subset,section-method`, `summary,section-method`

### Examples

    # Gulf Stream
    library(oce)
    data(section)
    GS <- subset(section, 109<=stationId&stationId<=129)
    GSg <- sectionGrid(GS, p=seq(0, 5000, 100))
    plot(GSg, map.xlim=c(-80,-60))

[Package oce version 1.0-1 Index]