PresenceAbsence is a new S3 object class created
and used inside the
letsR package. This object class is used to
store information on species distribution within a geographic domain in the form of
a presence-absence matrix. In addition, the
PresenceAbsence object also contains
other essential information (e.g. user-defined grid cell system, including resolution,
projection, datum, and extent) necessary for other analysis performed with the package's functions.
Creating a PresenceAbsence object
PresenceAbsence object can be generated using the following
The PresenceAbsence information
The result is a
list object of class
PresenceAbsence that includes the
- Presence_and_Absence_Matrix: A matrix of species' presence(1) and absence(0) information. The first two columns contain the longitude (x) and latitude (y) of the cells' centroid (from the gridded domain used);
- Richness_Raster: A raster containing species richness information across the geographic domain, which can be used to map the observed geographic gradient in species richness;
- Species_name: A character vector with species' names contained in the matrix.
Each of the objects can be obtained usign the standard subsetting operators that are commonly applied to a
list object (i.e. '[[' and '$').
letsR functions applied to a PresenceAbsence object
The following functions from the letsR package can be directly applied to a
Generic functions applied to a PresenceAbsence object
The following generic functions can be directly applied to the
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