Combine Measurements of Events
Combine measurements associated with events that occur in the same polygon.
combineEvents (events, locs, FUN, ..., bdryOK = TRUE)
events |
EventData with at least four columns ( |
locs |
LocationSet usually resulting from a call to
|
FUN |
a function that produces a scalar from a vector
(e.g., |
... |
optional arguments for |
bdryOK |
Boolean value; if |
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.
PolyData with columns PID, SID (if in
locs), and Z.
Nicholas M. Boers, Associate Professor – Computer Science
MacEwan University, Edmonton AB
Last modified Rd: 2013-04-10
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))
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