A PolyData object comprises a data frame that summarises information
for each polyline/polygon in a PolySet; each PolyData record is defined by
a unique PID or (PID, SID combination).
PBSmapping functions that expect PolyData will accept properly formatted data frames in their place (see 'Details').
as.PolyData attempts to coerce a data frame to an object with
class PolyData.
is.PolyData returns TRUE if its argument is of class
PolyData.
as.PolyData(x, projection = NULL, zone = NULL)
is.PolyData(x, fullValidation = TRUE)The as.PolyData method returns an object with classes
"PolyData" and "data.frame", in that order.
data frame to be coerced or tested.
optional projection attribute to add to
PolyData, possibly overwriting an existing attribute.
optional zone attribute to add to PolyData,
possibly overwriting an existing attribute.
Boolean value; if TRUE, fully test
x.
Nicholas M. Boers, Staff Software Engineer
Jobber, Edmonton AB
Last modified Rd: 2015-04-23
We define PolyData as a data frame with a first column named PID
and (optionally) a second column named SID. Unlike a
PolySet, where each contour has many records corresponding
to the vertices, a PolyData object must have only one record for each
PID or each (PID, SID) combination. Conceptually,
this object associates data with contours, where the data correspond to
additional fields in the data frame. The R language conveniently
allows data frames to contain fields of various atomic modes
("logical", "numeric", "complex",
"character", and "null"). For example, PolyData with the
fields (PID, PName) might assign character names to a set
of primary polygons. Additionally, if fields X and Y exist
(perhaps representing locations for placing labels), consider adding
attributes zone and projection. Inserting the string
"PolyData" as the class attribute's first element alters the
behaviour of some functions, including print (if
PBSprint is TRUE) and summary.
Our software particularly uses PolyData to set various plotting
characteristics. Consistent with graphical parameters used by the R/S
functions lines and polygon, column names
can specify graphical properties:
lty - line type in drawing the border and/or shading
lines;
col - line or fill colour;
border - border colour;
density - density of shading lines;
angle - angle of shading lines.
When drawing polylines (as opposed to closed polygons), only lty
and col have meaning.
PolySet, EventData, LocationSet