[R-sig-Geo] missing changelog in maptools 0.4.11

Roger Bivand Roger.Bivand at nhh.no
Tue Feb 22 10:17:14 CET 2005

On Tue, 22 Feb 2005, Susumu Tanimura wrote:

> Dear Roger Bivand
> Since I noticed a new version of maptools, I upgraded the maptools and then 
> checked the changelog.
> > maptools(changes=T)
> maptools, version 0.4-11, 2005-01-17
> [snip]
> 0.4-10 Function write.linelistShape() added to output a list of lines to a 
> 0.4-10 shapefile, as suggested by Patrick Giraudoux.
> So, no changelog of version 0.4.11 was given.  It is nice if you show
> us the change.

Thanks for keeping me alert! The entry is: "Adding checks for length()  
being zero", so no changes to functionality. The problem is that when
length(x) is 0, 1:0 produces indices for the loop for (i in 1:length(x)),
but should omit the loop if length(x) is 0. 0.4-12 will be coming soon,
and will have the required information in the changes file.

Can I ask whether I should continue to provide the current plot order 
heurisitic as an option - I am considering dropping the present scheme, 
which tries to guess the ring direction and plot order of polygons and 
sub-polygons form their inclusion inside each other. The reason for 
dropping it as default (for Map2poly(..., raw=FALSE)) is a user report of 
an otherwise valid shapefile generating a plot order which was corrupted 
(had one polygon of 1750 missing).

The new approach is to force all single polygons to be clockwise, and to 
plot them from largest to smallest. For multipolygons, the largest 
sub-polygon will be clockwise, and plotted first, and included 
sub-polygons will have their ring directions switched to anti-clockwise if 
included in another subpolygon of the multipolygon.

This scheme will also be used in the up-coming sp package, so please 
express your views now!

Best wishes,


> --
> Susumu Tanimura
> Dept. of Socio-environmental Medicine
> Inst. of Tropical Medicine, Nagasaki University
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Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Breiviksveien 40, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93
e-mail: Roger.Bivand at nhh.no

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