combineEvents function

Combine Measurements of Events

Combine measurements associated with events that occur in the same polygon.

combineEvents (events, locs, FUN, ..., bdryOK = TRUE)

Arguments

• events: EventData with at least four columns (EID, X, Y, Z).
• locs: LocationSet usually resulting from a call to findPolys.
• FUN: a function that produces a scalar from a vector (e.g., mean, sum).
• ...: optional arguments for FUN.
• bdryOK: Boolean value; if TRUE, include boundary points.

Details

This function combines measurements associated with events that occur in the same polygon. Each event (EID) has a corresponding measurement Z. The locs data frame (usually output from findPolys) places events within polygons. Thus, each polygon (PID, SID) determines a set of events within it, and a corresponding vector of measurements Zv. The function returns FUN(Zv), a summary of measurements within each polygon.

Returns

PolyData with columns PID, SID (if in

locs), and Z.

Author(s)

Nicholas M. Boers, Staff Software Engineer

Jobber, Edmonton AB

Last modified Rd: 2013-04-10

See Also

findCells, findPolys, locateEvents, locatePolys, makeGrid, makeProps.

Examples

local(envir=.PBSmapEnv,expr={
  #--- create an EventData data frame: let each event have Z = 1
  events <- data.frame(EID=1:10, X=1:10, Y=1:10, Z=rep(1, 10))
  #--- example output from findPolys where 1 event occurred in the first
  #--- polygon, 3 in the second, and 6 in the third
  locs <- data.frame(EID=1:10,PID=c(rep(1,1),rep(2,3),rep(3,6)),Bdry=rep(0,10))
  #--- sum the Z column of the events in each polygon, and print the result
  print(combineEvents(events=events, locs=locs, FUN=sum))
})