[R-sig-Geo] API documentation?

[David Hugh-Jones]

Guys

I don't mean to rant, but believe me, I've spent plenty of time with
the documentation and it's really not helping.

Partly this is a problem of R's doc format which treats package
documentation as an alphabetical list of functions - which gives me no
idea where to start.

This then interacts badly with the OO structure. For example, look at
the 20+ pages on "coerce". Hmm, what does "coerce" actually do? In
fact that's in a whole different library. But I didn't know that, so I
click on a page at random, say

coerce,SpatialGrid,data.frame-method

and this takes me to SpatialGrid class - which doesn't mention coerce
at all. (Nor does it tell me what SpatialGrid is, or what it is used
for.)

On the other hand, maybe I might guess that to get a list of
coordinates, I'd use "coordinates". So I click on that method, and it
tells me yes, this "retrieves spatial coordinates". But unfortunately
it retrieves them hidden inside another object ("an object of class
SpatialPointsDataFrame"). OK, but how do I get the _actual_data_?
Maybe the SpatialPointsDataFrame class page will tell me. Nope. Et
cetera.

Rick: yes, I agree that using the internal data structures is how to
do things, but this is broken isn't it? The whole point of having OO
is to be able to use it _without_ understanding the internal data
structures. The ideal, in other words, would be to have a "thin.lines"
method that I could just run on any polygon or set of polygons.
Failing that, then I should be able to get at the internal data
without hours of head scratching.

Right now, it's like, everything is hidden behind a layer of classes
and slots and methods, but I still need to go behind that layer to get
at the actual raw data, and this is so complicated and confusing that
it would be easier just to work with the raw data.

OK, I'll stop venting. If there's anything I could do to improve this
situation, I would gladly try.

David Hugh-Jones
PhD Candidate
Essex University Department of Government
http://davidhughjones.googlepages.com


2008/6/30 Virgilio Gomez-Rubio <v.gomezrubio at imperial.ac.uk>:
> Dear David,
>
> Probably the best way to start is by checking the HTML documentation. It
> should be installed locally but it is also accesible, for example, here:
>
> http://finzi.psych.upenn.edu/R/library/sp/html/00Index.html
>
> Hope this helps.
>
> Virgilio
>
> On Mon, 2008-06-30 at 18:48 +0200, David Hugh-Jones wrote:
>> Thanks David for his comment about dp.
>>
>> Quick question: is there any reasonably comprehensible API
>> documentation for the "sp" package? I have just spent about an hour
>> trying to get a list of points from a SpatialPolygons object. I
>> eventually just printed everything out and found the data by hand, so
>> now I am doing:
>>
>> coords <- myobject at polygons[[1]]@Polygons[[1]]@coords
>>
>> but I don't assume that is right. Surely there must be some simple way
>> to get a list of x and y coords out of any object?
>>
>> in frustration,
>> David Hugh-Jones
>> PhD Candidate
>> Essex University Department of Government
>> http://davidhughjones.googlepages.com
>>
>>
>> 2008/6/30 David PINAUD <pinaud at cebc.cnrs.fr>:
>> > maybe you can try the function dp() in the package "shapefiles", which is an
>> > implementation of the Douglas-Peucker polyLine simplification algorithm.
>> > Hope it helps
>> > David
>> >
>> > David Hugh-Jones a écrit :
>> >>
>> >> Hi all
>> >>
>> >> I have a big dataset of points and am doing stuff on them that takes a
>> >> lot of time. To speed it up, I would like to use "thinlines" from
>> >> RArcinfo, which basically makes the maps "rougher" by throwing away
>> >> points. Is there an equivalent function for SpatialPolygon type
>> >> objects? (I assume that there's no way to convert _to_ Arcinfo, though
>> >> I know it's possible to read from it).
>> >>
>> >> Cheers
>> >>
>> >> David Hugh-Jones
>> >> PhD Candidate
>> >> Essex University Department of Government
>> >> http://davidhughjones.googlepages.com
>> >>
>> >> _______________________________________________
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>> >> R-sig-Geo at stat.math.ethz.ch
>> >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>> >>
>> >>
>> >>
>> >>
>> >
>> > --
>> > ***************************************************
>> > David PINAUD
>> > Ingénieur de Recherche "Analyses spatiales"
>> >
>> > Centre d'Etudes Biologiques de Chizé - CNRS UPR1934
>> > 79360 Villiers-en-Bois, France poste 485
>> > Tel: +33 (0)5.49.09.35.58
>> > Fax: +33 (0)5.49.09.65.26
>> > http://www.cebc.cnrs.fr/
>> >
>> > ***************************************************
>> >
>> >
>> >
>> >
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>> > http://www.eset.com
>>
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