R: Subset an Argo Object

subset,argo-method {oce} | R Documentation

## Subset an Argo Object

### Description

Subset an argo object, either by selecting just the "adjusted" data or by subsetting by pressure or other variables.

### Usage

    ## S4 method for signature 'argo'
    subset(x, subset, ...)

### Arguments

`x` | an argo object.
`subset` | An expression indicating how to subset `x`.
`...` | optional arguments, of which only the first is examined. The only possibility is `within`, a polygon enclosing data to be retained. This must be either a list or data frame, containing items named either `x` and `y` or `longitude` and `latitude`; see Example 4. If `within` is given, then `subset` is ignored.

### Details

If `subset` is the string `"adjusted"`, then `subset` replaces the station variables with their adjusted counterparts. In the argo notation, e.g. `PSAL` is replaced with `PSAL_ADJUSTED`; in the present notation, this means that `salinity` in the `data` slot is replaced with `salinityAdjusted`, and the latter is deleted. Similar replacements are also done with the flags stored in the `metadata` slot.

If `subset` is an expression, then the action is somewhat similar to other `subset` functions, but with the restriction that only one independent variable may be used in in any call to the function, so that repeated calls will be necessary to subset based on more than one independent variable. Subsetting may be done by anything stored in the data, e.g. `time`, `latitude`, `longitude`, `profile`, `dataMode`, or `pressure` or by `profile` (a made-up variable) or `id` (from the `metadata` slot). Note that subsetting by `pressure` preserves matrix shape, by setting discarded values to `NA`, as opposed to dropping data (as is the case with `time`, for example).

### Value

An argo object.

### Author(s)

Dan Kelley

### See Also

Other things related to argo data: `[[,argo-method`, `[[<-,argo-method`, `argo-class`, `argoGrid()`, `argoNames2oceNames()`, `argo`, `as.argo()`, `handleFlags,argo-method`, `plot,argo-method`, `read.argo()`, `summary,argo-method`

Other functions that subset oce objects: `subset,adp-method`, `subset,adv-method`, `subset,amsr-method`, `subset,cm-method`, `subset,coastline-method`, `subset,ctd-method`, `subset,echosounder-method`, `subset,lobo-method`, `subset,met-method`, `subset,oce-method`, `subset,odf-method`, `subset,rsk-method`, `subset,sealevel-method`, `subset,section-method`, `subset,topo-method`, `subset,xbt-method`

### Examples

    library(oce)
    data(argo)

    # Example 1: buset by time, longitude, and pressure
    par(mfrow=c(2,2))
    plot(argo)
    plot(subset(argo, time > mean(time)))
    plot(subset(argo, longitude > mean(longitude)))
    plot(subset(argoGrid(argo), pressure > 500 & pressure < 1000), which=5)

    # Example 2: restrict attention to delayed-mode profiles.
    par(mfrow=c(1, 1))
    plot(subset(argo, dataMode == "D"))

    # Example 3: contrast corrected and uncorrected data
    par(mfrow=c(1,2))
    plotTS(argo)
    plotTS(subset(argo, "adjusted"))

    # Example 4. Subset by a polygon determined with locator()
    ## Not run:
    par(mfrow=c(2, 1))
    plot(argo, which="map")
    bdy <- locator(4) # Click the mouse on 4 boundary points
    argoSubset <- subset(argo, within=bdy)
    plot(argoSubset, which="map")

    ## End(Not run)

[Package oce version 1.2-0 Index]