[R-sig-Geo] Indian GIS data

[Jason Dalton]

There is a small repository of geodata for India at:
http://data.geocomm.com/catalog/IN/datalist.html



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Today's Topics:

   1. Re: [R] Map archives (Roger Bivand)


----------------------------------------------------------------------

Message: 1
Date: Mon, 20 Mar 2006 08:41:51 +0100 (CET)
From: Roger Bivand <Roger.Bivand at nhh.no>
Subject: Re: [R-sig-Geo] [R] Map archives
To: Alexander Nervedi <alexnerdy at hotmail.com>
Cc: r-sig-geo at stat.math.ethz.ch
Message-ID: <Pine.LNX.4.44.0603200809580.7028-100000 at reclus.nhh.no>
Content-Type: TEXT/PLAIN; charset=US-ASCII

On Mon, 20 Mar 2006, Alexander Nervedi wrote:

> 
> Hi R Map packages users.
> 
> I just drew my first few plots using map() and am trying to see if I can 
> configure it to my needs. Are there any known archives out there from
where 
> I can get additional data files for the map library to read? I am 
> specifically look for sub-district level administrative boundary lines for

> Madhya Pradesh, India. Kind of like county lines I guess.

The short answer is that you need access to the data first, there are no 
repositories of this kind.

Geospatial data are generally available only for the US in the public 
domain, and so could be made into geographical databases for the map 
package. So for the US, you get county lines for a specific date. The 
functions in the map package are specifically suited to the representation 
of borders used in the cited references under ?map, by Becker and Wilks, 
1993 and 1995, and do not integrate well with contemporary GIS data 
formats. 

The main question is whether you can find or purchase suitable boundary 
files in any format. That will likely absorb 95% of the effort, I'm 
afraid.

Once you've done that, you can consider converting them to map package
format, which can be done but involves jumping through the hoops described
by Becker and Wilks. We don't yet have a convenient way of priming the
Becker/Wilks build train with external data from the sp package
SpatialPolygons class, but it is quite possible that this could be done if
there was enough interest.

Alternatively, you can use the maptools or shapefiles packages to read
shapefiles, RArcInfo to read ArcINFO v7 binary vector files, or rgdal to
read a wide selection of formats (extra drivers can be compiled in if you
install from source). 

You can also convert the data you have found to suit a format that can be
read into R externally, using either open source or proprietary software.
Quite often the data formats are also specific to the providing
organisations.  

It remains the case that digitising heads-up on-screen from a scanned
paper map is the only practical solution in many cases, especially when
historical boundaries are needed.

Googling on Madhya Pradesh shapefile got to the gisindia list, where a 
correspondent replies:

"u can write to Survey of India, Dehradun, they have shape files of all
states of India along with district boundary."

which looks hopeful (if district them probably also sub-district), but
you'd need to talk to people probably locally to try to get hold of
suitable shapefiles.

The next hurdle is to match the spatial representation to your observation 
units - are all the sub-polygons of a sub-district level authority 
separate objects, or grouped together? How are they tagged with unique 
IDs? This matters, because GIS data is collected for many purposes, and 
complete polygon sets for thematic mapping is not the most important.

It would be really nice if there was a repository of these kinds of data, 
especially if they were not limited in use, but there is a long way to go 
before everywhere else catches up with the US.

Roger

> 
> thanks.
> Aleks
> 
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-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, 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



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End of R-sig-Geo Digest, Vol 31, Issue 13