HI, thanks Barry, I am also one of those converters, I started with an shp
file, and optimized it into topojson, what I mean is that i also have that
shp file. The problem is that it is huge.

Right, as a json, I could use a json r library, so then my question is
more: *does exists a r library that understands geojson or topojson and
prints maps in these formats?*
As d3.js does. Probably I could try with shiny, as I've read a few times
some shiny+d3.js examples, but I was looking for a one library solution, or
the fewer code lines as possible.

BR,

Miguel


Saludos,

                Miguel Fiandor


2013/12/16 Barry Rowlingson <b.rowlingson@lancaster.ac.uk>

> On a more positive note, topojson, like geojson, is just a JSON file,
> so you can read it with any of the R JSON interface packages (I've
> just read a us.json file using package:RJSONIO).
>
>  The job is then to unweave the structure into something plottable.
> topojson works by defining features as sequences of arcs, and arcs as
> sequences of coordinates. The arcs are actually defined as a start
> point and x-y offsets.
>
>  With a whole load of array lookups (remembering that arc -342 is arc
> 342 in the reverse direction) you could write some R code to go from
> topojson to SpatialPolygons.
>
>  I'm loathe to do this at the moment since I suspect the functionality
> to convert from topojson to shapefiles/geojson/some other standard
> exists (apart from in ogr 2.0) and it would be easier to re-use that.
>
>  Ooh, it takes me back to my reverse-engineering Arc/Info .e00 files...
>
> Barry
>
>
> On Mon, Dec 16, 2013 at 10:31 AM, Barry Rowlingson
> <b.rowlingson@lancaster.ac.uk> wrote:
> > The geoJSON driver in gdal/ogr will read it from version 2 of OGR:
> >
> > http://www.gdal.org/ogr/drv_geojson.html
> >
> > but I think that's very leading-edge (I seem to have v 1.10  on my
> system).
> >
> > So the solution would seem to be to convert your topojson to something
> > that your gdal/ogr can handle, and then read it into R using the rgdal
> > package readOGR function. I'm having trouble finding a utility that
> > will do the conversion that way, since most people start from
> > something and convert it _to_ topojson for fast rendering! I think it
> > might be necessary to cruft something  together from various python or
> > javascript modules lying around the web,
> >
> > From there its straightforward SpatialPolygonsDataFrame stuff.
> >
> > Barry
> >
> > On Sun, Dec 15, 2013 at 10:49 PM, Miguel Fiandor Gutiérrez
> > <mfiandor@gmail.com> wrote:
> >> Hi,
> >>
> >> I do have some maps in topojson format, and I would like to display
> data on
> >> them that i have in .CSVs and access database. So far I play with them
> with
> >> d3.js,<
> http://transparenciadecuentaspublicas.es/2012/madrid/gastos-personales>but
> >> i'd like to learn too with R.
> >> My question is not about the csv or db to data frame or similar, is how
> to
> >> display any data variable with this kind of map files, I have not found
> >> literature about it. Yes, each region of the map has its own id code.
> >>
> >> The output will end on a pdf file or website, but as soon as I can print
> >> the map or export it it would be enough.
> >>
> >> Thanks
> >>
> >> Miguel Fiandor
> >>
> >>         [[alternative HTML version deleted]]
> >>
> >> _______________________________________________
> >> R-sig-Geo mailing list
> >> R-sig-Geo@r-project.org
> >> https://stat.ethz.ch/mailman/listinfo/r-sig-geo
>

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