# as.geodata

##### Converts an Object to the Class "geodata"

The default method converts a matrix or a data-frame
to an object of the
`class`

`"geodata"`

.
Objects of the class `"geodata"`

are lists with two obligatory
components: `coords`

and `data`

.
Optional components are allowed and a typical example is a vector or
matrix with covariate(s) values.

##### Usage

`as.geodata(obj, …)`# S3 method for default
as.geodata(obj, coords.col = 1:2, data.col = 3, data.names = NULL,
covar.col = NULL, covar.names = "obj.names",
units.m.col = NULL, realisations = NULL,
na.action = c("ifany", "ifdata", "ifcovar", "none"),
rep.data.action, rep.covar.action, rep.units.action,
...)

# S3 method for geodata
as.data.frame(x, …, borders = TRUE)

# S3 method for geodata.frame
as.geodata(obj, …)

# S3 method for SpatialPointsDataFrame
as.geodata(obj, data.col = 1, …)

is.geodata(x)

##### Arguments

- obj
a matrix or data-frame where each line corresponds to one spatial location. It should contain values of 2D coordinates, data and, optionally, covariate(s) value(s) at the locations. A method for

`SpatialPointsDataFrame`

is also provided. It can also take an output of the function`grf`

, see DETAILS below.- coords.col
a vector with the column numbers corresponding to the spatial coordinates.

- data.col
a scalar or vector with column number(s) corresponding to the data.

- data.names
optional. A string or vector of strings with names for the data columns. Only valid if there is more than one column of data. By default, takes the names from the original object.

- covar.col
optional. A scalar or numeric vector with the column number(s) corresponding to the covariate(s). Alternativelly can be a character vector with the names of the covariates.

- covar.names
optional. A string or vector of strings with the name(s) of the covariates. By default take the names from the original object.

- units.m.col
optional. A scalar with the column number corresponding to the offset variable. Alternativelly can be a character vector with the name of the offset. This option is particularly relevant when using the package geoRglm. All values must be greater then zero.

- realisations
optional. A vector indicating the realisation number or a number indicating a column in

`obj`

with the realisation indicator variable. See`DETAILS`

below.- na.action
string defining action to be taken in the presence of

`NA`

's. The default option`"ifany"`

excludes all points for which there are`NA`

's in the data or covariates. The option`"ifdata"`

excludes points for which there are`NA`

's in the data. The default option`"ifcovar"`

excludes all points for which there are`NA`

's in the covariates. The option`"none"`

do not exclude points.- rep.data.action
a string or a function. Defines action to be taken when there is more than one data at the same location. The default option

`"none"`

keeps the repeated locations, if any. The option`"first"`

retains only the first data recorded at each location. Alternativelly a function can be passed and it will be used. For instance if`mean`

is provided, the function will compute and return the average of the data at coincident locations. The non-default options will eliminate the repeated locations.- rep.covar.action
idem to

`rep.data.locations`

, to be applied to the covariates, if any. Defaults to the same option set for`rep.data.locations`

.- x
an object which is tested for the class

`geodata`

.- rep.units.action
a string or a function. Defines action to be taken on the element

`units.m`

, if present when there is more than one data at the same location. The default option is the same value set for`rep.data.action`

.- borders
logical. If TRUE the element borders in the

`geodata`

object is set as an attribute of the data-frame.- …
values to be passed for the methods.

##### Details

Objects of the class `"geodata"`

contain data for
geostatistical analysis using the package geoR.
Storing data in this format facilitates the usage of the functions in geoR.
However, conversion of objects to this class is not obligatory
to carry out the analysis.

`NA`

's are not allowed in the coordinates. By default the
respective rows will not be included in the output.

**Realisations**
Tipically geostatistical data correspond to a unique realisation of
the spatial process.
However, sometimes different "realisations" are possible.
For instance, if data are collected in the same area at different
points in time and independence between time points is assumed,
each time can be considered a different "replicate" or "realisation"
of the same process. The argument `realisations`

takes a vector
indication the replication number and can be passed to other geoR
functions as, for instance, `likfit`

.

The data format is similar to the usual `geodata`

format in
geoR.
Suppose there are realisations (times) \(1, \ldots, J\)
and for each realisations \(n_1, ..., n_j\) observations are available.
The coordinates for different realisations
should be combined in a single \(n \times 2\) object,
where \(n=n_1 + \ldots + n_J\).
Similarly for the data vector and covariates (if any).

**grf objects**
If an object of the class `grf`

is provided the functions just
extracts the elements `coords`

and `data`

of this object.

##### Value

An object of the `class`

`"geodata"`

which is a list
with two obligatory components (coords and data)
and other optional components:

an \(n \times 2\) matrix where \(n\) is the number of spatial locations.

a vector of length \(n\), for the univariate case or, an \(n \times v\) matrix or data-frame for the multivariate case, where \(v\) is the number of variables.

a vector of length \(n\) or an \(n \times p\) matrix with covariate(s) values, where \(p\) is the number of covariates. Only returned if covariates are provided.

a vector on size \(n\) with the replication number. Only returned if argument realisations is provided.

##### References

Further information on the package geoR can be found at: http://www.leg.ufpr.br/geoR.

##### See Also

`read.geodata`

for reading data from an
*ASCII* file and `list`

for general information on lists.

##### Examples

```
# NOT RUN {
## converting the data-set "topo" from the package MASS (VR's bundle)
## to the geodata format:
if(require(MASS)){
topo
topogeo <- as.geodata(topo)
names(topogeo)
topogeo
}
# }
```

*Documentation reproduced from package geoR, version 1.8-1, License: GPL (>= 2)*