Create and manipulate a window of analysis for landscape descriptors used in AURELHY

Description

An AURELHY window of analysis ('auremask' object) specifies the regions relative to the point that define the various variables describing the landscape.

Usage

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auremask(type = "radial", dist = c(1, 6, 11, 16, 21, 26),
    angles = 0:7 * pi/4 + 0.01, n = 11, keep.origin = FALSE)

## S3 method for class 'auremask'
print(x, geomat, ...)
## S3 method for class 'auremask'
plot(x, y, ...)

Arguments

type

the type of window, either "radial" (by default), or "rectangular" as in the initial version of the AURELHY method.

dist

A vector of distances (in km) to consider in the window for the "radial" window, or the distance to consider between two grid points for a "rectangular" window (in this case, if you provide several distances, only the smallest one will be considered)

angles

A vector of angles in radians to use to construct a "radial" window. This argument is ignored for "rectangular" window. Avoid to use angles parallels to the grid, like 0 or pi/4, because you will have points going into one or the other sector of your window of analysis, depending on rounding of the numbers in the floating-point calculations! A slight shift angle (0.01, by default) avoids this unstability

n

The number of grid points in latitude and longitude to use for a "rectangular" window. For instance, if n = 11, the window will be made of 11*11 = 121 points (minus one if keep.origin is FALSE). This argument is ignored for a "radial" window.

keep.origin

Is the origin where the window is centered considered as one point of the grid, or not (by default, not, as in the original implementation of the AURELHY method)

x

An 'auremask' object

geomat

A reference grid, as a 'geomat' object against which the window of analysis is tested (print or plot the number of points that are located in each sector of the window)

y

Same as geomat

...

further arguments passed to the function

Details

auremask() creates a new window of analysis. The object has print() and plot() methods.

Value

An 'auremask' object with all information required to mask a 'geotm' object (terrain model) for creating landscape variables required by the AURELHY method.

Author(s)

Philippe Grosjean <phgrosjean@sciviews.org>

See Also

polar.coords, geomat

Examples

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# Default window of analysis
am <- auremask()
am
# Get an example terrain model and apply the window on it
data(morocco)
plot(am, morocco)
# Further statistics are displayed with print() if a grid is provided too
print(am, morocco)