writing polygons/segments to shapefiles (.shp) or other ArCGIS compatible file

I am not sure a previous e-mail reached the list (no mail aknowledgement 
from R-boundle etc.). The question was how to write polygon
or segment coordinates into a shapefile set or any other ArcGIS supported 
format. The library shapefiles seems to do something but
the documentation is a bit beyond of my mind.... and I cannot get the 
meaning of the functions write**** and its application to the
case below:

In simple words, is there a somewhere a function taking polygon 
coordinates (or simple segments) within R to a "ready to read" set
of files ***.shp, ***.shx, etc...

Thanks in advance for any hint

Patrick



----- Original Message -----
From: "Patrick Giraudoux" <patrick.giraudoux at univ-fcomte.fr>
To: "r-help" <r-help at stat.math.ethz.ch>
Sent: Wednesday, February 25, 2004 1:08 PM
Subject: writing polygons/segments to shapefiles (.shp)

Dear all,

The library maptools offers a fantastic support for shapefile reading.

Is there a R library available permitting the writing of polygon or 

segment coordinates into shapefile?

Thanks for any hint,

Patrick Giraudoux

I am not sure a previous e-mail reached the list (no mail aknowledgement 
from R-boundle etc.). The question was how to write polygon
or segment coordinates into a shapefile set or any other ArcGIS supported 
format. The library shapefiles seems to do something but
the documentation is a bit beyond of my mind.... and I cannot get the 
meaning of the functions write**** and its application to the
case below:

In simple words, is there a somewhere a function taking polygon 
coordinates (or simple segments) within R to a "ready to read" set
of files ***.shp, ***.shx, etc...

Thanks in advance for any hint

Patrick



----- Original Message -----
From: "Patrick Giraudoux" <patrick.giraudoux at univ-fcomte.fr>
To: "r-help" <r-help at stat.math.ethz.ch>
Sent: Wednesday, February 25, 2004 1:08 PM
Subject: writing polygons/segments to shapefiles (.shp)

Dear all,

The library maptools offers a fantastic support for shapefile reading.

Is there a R library available permitting the writing of polygon or 

segment coordinates into shapefile?

Thanks for any hint,

Patrick Giraudoux

There is a little problem with the approach I described in my previous email.
In ADE-4, coordinates are given in pixel and so Y are inverted. You must
invert your Y coordinates to obtain the good representation in ArcView. An
example:

 > library(ade4)
 > library(shapefiles)
 > library(maptools)
 > try1 <- read.shapefile(paste(ShapeDir, "columbus", sep="/"))
 > shppolys <- shape2poly(try1, as.character(try1$dbf$dbf$NEIGNO))
 > obj=poly2area(shppolys)
 > obj[,3]=-obj[,3]
 > write.table(obj,"try.area",col.names=F,quote=F,row.names=F)
 >

Then, use the 'From AREA' function in AVADE.



At 10:32 25/02/2004, Patrick Giraudoux wrote:

I am not sure a previous e-mail reached the list (no mail aknowledgement
from R-boundle etc.). The question was how to write polygon
or segment coordinates into a shapefile set or any other ArcGIS supported
format. The library shapefiles seems to do something but
the documentation is a bit beyond of my mind.... and I cannot get the
meaning of the functions write**** and its application to the
case below:

In simple words, is there a somewhere a function taking polygon
coordinates (or simple segments) within R to a "ready to read" set
of files ***.shp, ***.shx, etc...

Thanks in advance for any hint

Patrick



----- Original Message -----
From: "Patrick Giraudoux" <patrick.giraudoux at univ-fcomte.fr>
To: "r-help" <r-help at stat.math.ethz.ch>
Sent: Wednesday, February 25, 2004 1:08 PM
Subject: writing polygons/segments to shapefiles (.shp)

Dear all,

The library maptools offers a fantastic support for shapefile reading.

Is there a R library available permitting the writing of polygon or

segment coordinates into shapefile?

Thanks for any hint,

Patrick Giraudoux

St?phane DRAY
-------------------------------------------------------------------------------------------------- 

D?partement des Sciences Biologiques
Universit? de Montr?al, C.P. 6128, succursale centre-ville
Montr?al, Qu?bec H3C 3J7, Canada

Tel : 514 343 6111 poste 1233
E-mail : stephane.dray at umontreal.ca
-------------------------------------------------------------------------------------------------- 

Web                                          http://www.steph280.freesurf.fr/
-------------------------------------------------------------------------------------------------- 

Thanks a lot for the hints. I will try.  Actually I was focusing (in a first stage) on simple segments (small mammal traplines...).
I turned the problem out writing some lines to export the coordinates into a "simple" GRASS ascii file, imported it into GRASS as
vector file and then used the export tool to get  shapefiles...  Not that direct: needs to have GRASS installed and an elementary
knowledge on the export/import commands in this open source GIS.

It would be fantastic to have the reverse functions of Map2poly(Map), Map2lines(Map), Map2points(Map) read.shape (eg poly2map,
lines2map, points2map, and write.map) to write shapefiles.... I must however admit that I don't know enough about shapefile formats
and R programming to do this by myself... and I would unfortunately be really out of my current job in the university...