R: Subset a Coastline Object

subset,coastline-method {oce} | R Documentation

## Subset a Coastline Object

### Description

Subsets a coastline object according to limiting values for longitude and latitude. The raster package must be installed for this to work, because it relies on the `intersect` function from that package.

### Usage

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

### Arguments

`x` | A `coastline` object, i.e. one inheriting from `coastline-class`.
`subset` | An expression indicating how to subset `x`. See “Details”.
`...` | optional additional arguments, the only one of which is considered is one named `debug`, an integer that controlls the level of debugging. If this is not supplied, `debug` is assumed to be 0, meaning no debugging. If it is 1, the steps of determining the bounding box are shown. If it is 2 or larger, then additional processing steps are shown, including the extraction of every polygon involved in the final result.

### Details

As illustrated in the “Examples”, `subset` must be an expression that indicates limits on `latitude` and `longitude`. The individual elements are provided in R notation, not mathematical notation (i.e. `30<latitude<60` would not work). Ampersands must be used to combine the limits. The simplest way to understand this is to copy the example directly, and then modify the stated limits. Note that `>` comparison is not permitted, and that `<` is converted to `<=` in the calculation. Similarly, `&&` is converted to `&`. Spaces in the expression are ignored. For convenience, `longitude` and and `latitude` may be abbreviated as `lon` and `lat`, as in the “Examples”.

### Value

A `coastline` object.

### Author(s)

Dan Kelley

### See Also

Other things related to coastline data: `[[,coastline-method`, `[[<-,coastline-method`, `as.coastline`, `coastline-class`, `coastlineBest`, `coastlineCut`, `coastlineWorld`, `download.coastline`, `plot,coastline-method`, `read.coastline.openstreetmap`, `read.coastline.shapefile`, `summary,coastline-method`

Other functions that subset oce objects: `subset,adp-method`, `subset,adv-method`, `subset,amsr-method`, `subset,argo-method`, `subset,cm-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`

### Examples

    library(oce)
    data(coastlineWorld)
    ## Eastern Canada
    cl <- subset(coastlineWorld, -80<lon & lon<-50 & 30<lat & lat<60)
    ## The plot demonstrates that the trimming is as requested.
    plot(cl, clon=-65, clat=45, span=6000)
    rect(-80, 30, -50, 60, bg="transparent", border="red")

[Package oce version 1.1-1 Index]