calc_box: Calculate the Standard Deviation Box

In aspace: Functions for Estimating Centrographic Statistics

Calculate the Standard Deviation Box

Description

The orthogonal dispersion of a set of points can be described using the standard deviation of the x- and y-coordinates of a set of point observations. The orthogonal dispersion can then be visualized with a Standard Deviation Box. This function computes the properties of the Standard Deviation Box (SD Box) from a set of point observations.

Usage

calc_box(id=1, centre.xy=NULL, calccentre=TRUE, weighted=FALSE,
weights=NULL, points=NULL, verbose=FALSE)

Arguments

id	A unique integer to identify a SD Box
centre.xy	A vector of length 2, containing the x- and y-coordinates of the geographic centre of the SD Box
calccentre	Boolean: Set to TRUE if the mean center is to be calculated
weighted	Boolean: Set to TRUE if the weighted mean center is to be computed with weighted coordinates
weights	Weights applied to point observations, number of weights should equal the number of observations
points	A 2-column matrix or data frame containing the set of point observations input to the calc_box function
verbose	Boolean: Set to TRUE if extensive feedback is desired on the standard output

Details

Use the LOCATIONS element in the output list object along with the ATTRIBUTES elements can be used to produce shapefiles or other vector point files for geographic data.

Value

The returned result is a list:

TYPE	The type of calculation results stored in the object: BOX, SDD, SDE, CMD, CF, or CF2PTS, MNC, MDC
DATE	The date and time that the function was run
ID	Identifier for the SD Box shape - it should be unique
LOCATIONS	Locations pertinent for the BOX that can be used with ATTRIBUTES if wishing to build a vector point file for geographic data outside of this pacakge.
FORPLOTTING	Coordinates and identifiers used for plotting by plot_box()
ATTRIBUTES	Attributes for the output BOX that can be used with LOCATIONS coordinates if wishing to build a vector point file for geographic data outside of this package.
id	Identifier for the SD Box shape - it should be unique
calccentre	Boolean: TRUE if the mean centre was estimated
weighted	Boolean: TRUE if the weighted mean centre was estimated
CENTRE.x	X-coordinate of the centre
CENTRE.y	Y-coordinate of the centre
SD.x	Orthogonal standard deviation in the x-axis
SD.y	Orthogonal standard deviation in the y-axis
Box.area	Area of the standard deviation box
NW.coord	North-west coordinates of SD Box
NE.coord	North-east coordinates of SD Box
SW.coord	South-west coordinates of SD Box
SE.coord	South-east coordinates of SD Box

Note

Results specific for plotting are stored in the FORPLOTTING element within the produced list object. Pass the entire object to plot_box() and the function automatically extracts this information. This function can be used on its own (once) or repetitively in a loop to process grouped point data stored in a larger table. When used repetitively, be sure to increment the id argument to ensure that each SD BOX has a unique identifier.

Author(s)

Tarmo K. Remmel, Randy Bui, Ron N. Buliung

See Also

calc_sdd, calc_sde, calc_cmd, calc_cf, calc_cf2pts, calc_mnc, calc_mdc, wtd.var

Examples

# BOX EXAMPLE
data(activities)
a <- calc_box(id=1, centre.xy=NULL, points=activities)
str(a)
print(a)

# IF THE RESULT OF THIS FUNCTION IS STORED TO AN OBJECT, THE plot_box()
# FUNCTION WILL TAKE THAT OBJECT AS INPUT FOR PLOTTING VIA THE datin ARGUMENT

# BOX TO SHAPEFILE EXAMPLE (REMOVE THE COMMENTS TO RUN)
# shp <- convert.to.shapefile(a$LOCATIONS, a$ATTRIBUTES, "id", 5)
# write.shapefile(shp, "BOX_Shape", arcgis=T)

aspace documentation built on May 29, 2024, 2:04 a.m.