Convert EventData/PolyData into a PolySet
convDP (data, xColumns, yColumns)
This function expects data to contain several X- and Y-columns.
For example, consider data with columns x1, y1,
x2, and y2. Suppose xColumns = c("x1", "x2") and
yColumns = c("y1", "y2"). The result will contain
nrow(data) polygons. Each one will have two vertices,
(x1, y1) and (x2, y2) and POS values 1 and 2,
respectively. If data includes an SID column, so will
the result.
If data contains an EID and not a PID column,
the function uses the EIDs as PIDs.
If data contains both PID and EID columns,
the function assumes it is PolyData and ignores the EID
column.
PolySet with the same PIDs as those given in data. If
data has an SID column, the result will include it.
Nicholas M. Boers, Associate Professor – Computer Science
MacEwan University, Edmonton AB
Last modified Rd: 2013-04-10
local(envir=.PBSmapEnv,expr={
oldpar = par(no.readonly=TRUE)
#--- create sample PolyData
polyData <- data.frame(PID=c(1, 2, 3),
x1=c(1, 3, 5), y1=c(1, 3, 2),
x2=c(1, 4, 5), y2=c(2, 4, 1),
x3=c(2, 4, 6), y3=c(2, 3, 1))
#--- print PolyData
print(polyData)
#--- make a PolySet from PolyData
polys <- convDP(polyData,
xColumns=c("x1", "x2", "x3"),
yColumns=c("y1", "y2", "y3"))
#--- print and plot the PolySet
print(polys)
plotLines(polys, xlim=c(0,7), ylim=c(0,5), col=2)
par(oldpar)
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