[R-sig-Geo] Mysterious (to me) behaviour of cbind() on an envelope -- ASDAR ch. 7

[D G Rossiter]

Dear r-sig-geo friends:

I am working through ASDAR (Applied Spatial Data Analysis with R) book using the code and datasets on the book's website http://www.asdar-book.org/.

In sppa_mod.R (code for Chapter 7) we are trying to bind a new column giving the point-pattern name to an object of class envelope:

>  Gresults <- rbind(envjap, envred, envcells)
>  class(Gresults)
[1] "envelope"   "fv"         "data.frame"
>  Gresults <- cbind(Gresults, DATASET=rep(c("JAPANESE", "REDWOOD", "CELLS"), each=length(r)))

but somehow the newly-bound column does not get the assigned name 'DATASET', but is assigned the name 'y':

> str(Gresults)
Classes 'fv' and 'data.frame':  144 obs. of  6 variables:
 $ r   : num  0 0.005 0.01 0.015 0.02 0.025 0.03 0.035 0.04 0.045 ...
 $ obs : num  0 0 0 0.0615 0.0615 ...
 $ theo: num  0 0.00509 0.02021 0.04491 0.07843 ...
 $ lo  : num  0 0 0 0 0 ...
 $ hi  : num  0 0.0625 0.0748 0.1427 0.1933 ...
 $ y   : Factor w/ 3 levels "CELLS","JAPANESE",..: 2 2 2 2 2 2 2 2 2 2 ...
....

somehow the envelope has been removed also. Then when I try to plot according to the following code:

> print(xyplot(obs~theo|DATASET , data=Gresults, type="l", ...

the classifying category is not found. If I replace DATASET with y the plot is shown as in Fig. 7.3.

Clearly the cbind() is somehow not preserving the assigned column name, despite the class being build on data.frame. Where it gets the 'y' from is also seriously mysterious to me.

Here's my version info. I started from a clean workspace and only loaded the packages as indicated.

> version
platform       x86_64-apple-darwin9.8.0
arch           x86_64
os             darwin9.8.0
system         x86_64, darwin9.8.0
status
major          2
minor          14.0
year           2011
month          10
day            31
svn rev        57496
language       R
version.string R version 2.14.0 (2011-10-31)

Package:            sp
Version:            0.9-94
Date:               2011-12-21

Package:            spatstat
Version:            1.25-2
Date:               2012-01-19

Thanks for any insight!

D. G. Rossiter
Senior University Lecturer
University of Twente, Faculty ITC
Hengelosestraat 99
PO Box 217, 7500 AE Enschede, the Netherlands (NL)
Phone:  +31-(0)53 4874 499
Fax:    +31-(0)53 4874 336
mailto:rossiter at itc.nl,  Internet: http://www.itc.nl/personal/rossiter




Faculty of Geo-Information Science and Earth Observation (ITC)
University of Twente
Chamber of Commerce: 501305360000

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