calc_mcp {aspace}R Documentation

Compute and plot a Minimum Convex Polygon (MCP)

Description

The geographical extent of a set of points on a Cartesian plane can be described using a Minimum Convex Polygon (MCP). The MCP is the minimum area polygon containing a set of point locations.

Usage

calc_mcp(id=1, destmat = activities, filename="MCP_Output.txt", verbose = FALSE, pct = 100, plot = TRUE, plotdest = TRUE)

Arguments

id Provide a unique integer to identify this MCP from others you may construct with other data points
destmat Two-column matrix or data frame of point coordinates
filename A character name for an ASCII output file
verbose Boolean: set to TRUE if extended processing feedback is wanted
pct Integer 0 <= pct <=100, the percentage of the MCP for which area is provided
plot Boolean: the MCP will be plotted if set to TRUE
plotdest Boolean: all points will be plotted if set to TRUE

Details

This function is most powerful when used repetitively within a loop to compute the MCP for subsets of points stored in a large data table.

Value

The result is a LIST

MCP.area The area of the MCP in hectares
MCP.pct The desired percentage of the MCP for which area is computed
MCP.coords A matrix containing MCP vertices. Each row represents a unique point, the first column contains x-coordinates, and the second, y-coordinates

Note

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 parameter to ensure that each MCP has a unique identifier. The output ASCII coordinate file can be further processed using the makeshapes function to generate an ESRI Shapefile for MCP polygons.

Author(s)

Tarmo K. Remmel

References

Builds upon MCP functions available in the adehabitat package

See Also

mcp, calc_sdd, calc_sde, makeshapes

Examples

  plot.new()
  calc_mcp(id=1, destmat = activities, filename="MCP_Output.txt", verbose = FALSE, pct = 100, plot = TRUE, plotdest = TRUE) 

[Package aspace version 1.2 Index]