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

[Roger Bivand]

On Fri, 3 Feb 2012, D G Rossiter wrote:

> 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':

Thanks for noting this. I've updated the online code to give the variable 
the name "y" instead of "DATASET" here, and in the F and K tests too. An 
erratum has also been added. The figures now show the envelopes as on book 
figures 7.3, 7.4 and 7.9. There was a further infelicity in that 
lpolygon() takes a col= rather than a fill= argument, changed in the 
online code for the figures.

Best wishes,

Roger

>
>> 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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-- 
Roger Bivand
Department of Economics, NHH Norwegian School of Economics,
Helleveien 30, N-5045 Bergen, Norway.
voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no