class_geocontainer: GeoContainer: a container for point spatial data
In jeanmathieupotvin/cargo: Data containers, schemas and prototypes

Description Usage Arguments Details Value Slots The GeoContainer class Using the class Extending the GeoContainer class See Also

An extension of the Container class holding metadata and two-dimensional point spatial data.

GeoContainer(x, ...)

## S4 method for signature 'missing'
GeoContainer(
  x,
  schema = Schema(),
  xcol = character(),
  ycol = character(),
  crs = sp::CRS(),
  ...
)

## S4 method for signature 'character'
GeoContainer(
  x,
  schema = Schema(),
  xcol = character(),
  ycol = character(),
  crs = sp::CRS(),
  ...
)

## S4 method for signature 'data.frame'
GeoContainer(
  x,
  schema = Schema(),
  xcol = character(),
  ycol = character(),
  crs = sp::CRS(),
  ...
)

## S4 method for signature 'data.table'
GeoContainer(
  x,
  schema = Schema(),
  xcol = character(),
  ycol = character(),
  crs = sp::CRS(),
  ...
)

## S4 method for signature 'Schema'
GeoContainer(
  x,
  schema = Schema(),
  xcol = character(),
  ycol = character(),
  crs = sp::CRS(),
  ...
)

## S4 method for signature 'GeoContainer'
show(object)

`x`	conceptually, any R object. Typically, a `character`, a `data.frame`, a `data.table` or a `Schema`. See details. If missing, an empty object is initialized.
`...`	further arguments passed to or from other methods: if `x` is a character, `...` is passed to `safe_read_csv()`; if `x` is a `data.frame` or an object of class `Schema`, `...` is passed to `data.table::as.data.table()`.
`schema`	a `Schema` object. If `x` is itself an object of class `Schema`, it should be missing (it is ignored).
`xcol`	a character of length 1 naming a field in `x` that holds (east-west) spatial coordinates.
`ycol`	a character of length 1 naming a field in `x` that holds (north-south) spatial coordinates.
`crs`	either an integer of length 1 or an object of class `sp::CRS`. Passing an integer to this argument triggers an implicit conversion, see Details.
`object`	a `GeoContainer` object.

Passing objects of class `Schema` to `GeoContainer()`

If a Schema object is passed to GeoContainer(), an empty GeoContainer is generated. It will have empty columns defined with names and types matching the underlying Schema. Argument schema is ignored for that special case.

Passing integer values to the `crs` argument of `GeoContainer()`

The integer must represent a valid EPSG code (a standardized index for the underlying coordinates reference system). It must hold be recognized by the PROJ.4 projection system. To learn more on EPSG codes (or to search for one), use the excellent online API epsg.io.

The constructor function GeoContainer() returns an object of class GeoContainer.

The show() method returns NULL invisibly. It is used for its-effect.

table: a data.table. Its structure must match what slot schema prescribes.
schema: a Schema holding metadata (column names, types and prototypes) on the structure of table.'
xcol: a character. The name of the field in table that holds x (east-west) spatial coordinates.
ycol: a character. The name of the field in table that holds y (north-south) spatial coordinates.
crs: an object of class sp::CRS holding spatial coordinates' metadata. It must describe a valid Coordinates Reference System (CRS).

Class GeoContainer extends class Container for point data characterized by two-dimensional spatial coordinates. The added slots hold relevent spatial metadata. The class leverage recognized R packages sp and rgdal. Package cargo also includes some tools to work with spatial data.

An object of class GeoContainer also inherits class Container. This means that all features of the Container class can be used with objects of class GeoContainer.

Create objects of class GeoContainer through the constructor function GeoContainer().
Validate instances of the class by using valid_geocontainer().
Test objects for class GeoContainer with introspector function is_geocontainer().
Extract slots from instances of the class with functions table(), schema(), xcol(), ycol() and crs().
Extract spatial coordinates from instances of the class with function xy().
Set new values to slots with functions table<-(), schema<-(), xcol<-(), ycol<-() and crs<-().
Subset instances of the class by using the Container methods implemented for operators [, [[ and $.

Users should extend this class to a super-class with additional slots by using package methods only if their intent is to work with spatial data. Else, the Container class should be extended instead.

Other GeoContainer: GeoContainer-accessors, GeoContainer-methods, GeoContainer-validators, is_geocontainer()

jeanmathieupotvin/cargo documentation built on Oct. 27, 2020, 5:22 p.m.