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.
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)
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.
a vector with the column numbers corresponding to the spatial coordinates.
a scalar or vector with column number(s) corresponding to the data.
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.
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.
optional. A string or vector of strings with the name(s) of the covariates. By default take the names from the original object.
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.
optional. A vector indicating the realisation
number or a number indicating a column in obj with the
realisation indicator variable.
See DETAILS below.
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.
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.
idem to rep.data.locations, to be applied to
the covariates, if any. Defaults to
the same option set for rep.data.locations.
an object which is tested for the class geodata.
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.
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.
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.
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.
Further information on the package geoR can be found at: http://www.leg.ufpr.br/geoR.
read.geodata for reading data from an
ASCII file and list for general information on lists.
# 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
}
# }
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