[R] Unexpected behavior in PBSmapping package

[Haigh, Rowan]

Hi David,
Thanks for the message. Essentially, the argument 'col' is treated like
a vector which remains independent from (X,Y) and is simply repeated as
need for the number of points. If you specify
col=c("red","blue","green","yellow") as below, and there are only 2
points, only "red" and "blue" will be used (hence the perceived
mismatch).

To keep your colour column matched with X,Y, there is an argument called
polyProps that automatically looks for the column "col". Unfortunately,
polyProps doesn't appear to be functional with EventData (bug, I think)
but will work with PolyData. Take a look at the R-code below. I've
redefined your EventData to be PolyData which can serve double duty as
EventData and PolyData, i.e., you can pass "events" to plotPoints() as
well as using "polyProps=events". I've also added the "label" field to
events to simplify things, and used PBSmapping's addLabels() function. 

The plotPoints() code should have been able to do this with EventData
also. We will have to revisit this code. Thanks David for taking the
time to show us user-related problems. It helps us to re-evaluate
functionalities. Undoubtedly, the package has many little imperfections
but we try to iron them out over time.
Cheers, Rowan

### Begin Example ###
library( PBSmapping )

# Define some EventData
events <- as.PolyData( read.table( textConnection(
'PID X  Y  col
1 494 1494 red
2 497 1497 blue
3 500 1500 green
4 503 1503 yellow' ), header=TRUE, strings=FALSE ),
projection='UTM', zone=10 )
events$label <- toupper(substring(events$col,1,1));

par( mfrow=c(3,1) )

# Plot the events with plot limits large enough to show
# the full extent of all the symbols
plotPoints( events, pch=16, cex=5, polyProps=events,
   xlim=c(490,508), ylim=c(1490,1508),proj="UTM")
addLabels(events, polyProps=events, font=2, cex=2, col=1) 

# Normal plot extents; partial symbols cut off by edges
# of plotting region (as expected)
plotPoints( events, pch=16, cex=5, polyProps=events,proj="UTM")
addLabels(events, polyProps=events, font=2, cex=2, col=1) 

## Now use more-restrictive plot limits
plotPoints( events, pch=16, cex=5, polyProps=events,
   xlim=c(499,505), ylim=c(1499,1505),proj="UTM")
addLabels(events, polyProps=events, font=2, cex=2, col=1) 

### End example ###

P.S. Once you've defined your EventData/PolyData/PolySet with attribute
projection="UTM", plotMap() will attempt to use this but plotLines() and
plotPoints() will simply tell you if it matched the specified projection
in the function call. When you specified plotPoints(...,proj=TRUE), you
are probably overriding the earlier specified UTM projection (of events)
with proj=1. In this case, the 2 projections (UTM, 1) are the same. If
your Poly dataset was set to projection="LL", they would not be.
======================================================

-----Original Message-----
From: Schnute, Jon 
Sent: Monday, August 13, 2007 8:19 AM
To: Haigh, Rowan
Subject: FW: Unexpected behavior in PBSmapping package


Hi Rowan - Could you please check into this when you get a chance?
Thanks - Jon 

-----Original Message-----
From: D. Dailey [mailto:lists at CompassRoseEnterprises.com] 
Sent: Thursday, August 09, 2007 11:38 PM
To: r-help at stat.math.ethz.ch; Schnute, Jon
Subject: Unexpected behavior in PBSmapping package

Using R 2.5.1 on Windows XP Professional, and PBSmapping package version

2.51, I have encountered some behavior which puzzles me.  I am including

the package's listed maintainer on this email but also seek the thoughts

of the R-help community.

I have a set of EventData, which I want to plot as points, and to color 
the points according to some criterion.  It turns out that some of my 
points fall outside my desired plotting region.  It looks like this 
causes the PBSmapping functions plotPoints and addPoints to incorrectly 
deal with the color assignments.

Consider the following toy example:

### Begin Example ###

library( PBSmapping )

# Define some EventData
events <- as.EventData( read.table( textConnection(
'EID X  Y   Color
1 494 1494 red
2 497 1497 blue
3 500 1500 green
4 503 1503 yellow' ), header=TRUE, strings=FALSE ),
proj='UTM', zone=10 )

par( mfrow=c(3,1) )

# Plot the events with plot limits large enough to show
# the full extent of all the symbols
plotPoints( events, pch=16, cex=5, col=events$Color,
   xlim=c(490,508), ylim=c(1490,1508), proj=TRUE )
with( events, text( X, Y, toupper( substr( Color, 1, 1 ) ),
   font=2, cex=2 ) )

# Normal plot extents; partial symbols cut off by edges
# of plotting region (as expected)
plotPoints( events, pch=16, cex=5, col=events$Color, proj=TRUE )
with( events, text( X, Y, toupper( substr( Color, 1, 1 ) ),
   font=2, cex=2 ) )

## Now use more-restrictive plot limits
plotPoints( events, pch=16, cex=5, col=events$Color,
   xlim=c(499,505), ylim=c(1499,1505), proj=TRUE )
with( events, text( X, Y, toupper( substr( Color, 1, 1 ) ),
   font=2, cex=2 ) )
# Note that symbols are plotted in the right places (note text labels)
# but colors are not as expected

### End example ###


For the moment, I have worked around this issue by using a "with( 
events, points( ... ) )" construction, but this seems suboptimal; I 
would prefer to use addPoints (which exhibits the same problem as 
plotPoints does in the toy example above).  I would appreciate any 
insights those on the list might have.

Please include me directly on any reply to the list, as I am at least a 
couple weeks behind on reading the digested version of the list.  I see 
that there have been no mentions of the PBSmapping package even in the 
digests I have not yet read.

Session info:

 > sessionInfo()
R version 2.5.1 (2007-06-27)
i386-pc-mingw32

locale:
LC_COLLATE=English_United States.1252;LC_CTYPE=English_United 
States.1252;LC_MONETARY=English_United 
States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252

attached base packages:
[1] "stats"     "graphics"  "grDevices" "utils"     "datasets" 
"methods"   "base"

other attached packages:
PBSmapping
     "2.51"



--David Dailey
Shoreline, Washington, USA