newbie questions

tom sgouros <tomfool at as220.org> wrote:

Dan Putler <dan.putler at sauder.ubc.ca> wrote:

Er, what exactly is your data? Do you have data that is linked to zip
codes and you want to do a "thematic" (choropleth) map of the data? Do
you have point data (say a lat/lon values), and want to plot the points?
Given what you've said, hard to figure out how to get you going in the
right direction.

The data is mostly from past elections, so it's vote totals or
demographic data within some district.

I should have also said that I have both SHP files and E00 files to
describe the boundaries of the districts, but have no feeling about
which I should prefer or why and I wonder if anyone else does.  The SHP
files come with an XML description that seems not to be used by grass.
The E00 files maybe come with a description of their own projection,
while I had to identify a projection to specify it to grass, but
otherwise I don't know why one would be better or worse.

Thanks,

 -tom

Google tells me that choropleth is the name of precisely the kind of
thing I'm trying to make, thank you for expanding my vocabulary today.

Is there a name for the bar graph kind of thing?  (Here's an example:
http://www.turbosquid.com/FullPreview/Index.cfm/ID/346428 )

Thank you,

 -tom

On Sun, 2009-11-15 at 22:30 -0500, tom sgouros wrote:

Raphael Saldanha <saldanha.plangeo at gmail.com> wrote:

Hi Tom!

I'm a geographer and R enthusiast too, but what I can say is: R is a great
software to statistics. The final production of maps, although it's
possible, it's simple and faster made with GIS softwares, like GRASS,
Quantum GIS or ArcGIS.

This is exactly my quandary.  I have some data I want to map, and I have
no idea how to do it and none of the introductions I've found speak to
what I thought was a pretty simple task.

I first thought maybe I should use a GIS, since it's geographic data,
but all the GIS documentation I can find is about how to analyze data
that's already available.  There are no end of Grass examples using this
North Carolina dataset that comes with the installation, but I don't
live in North Carolina and I don't want to analyze their data.  I want
to analyze mine, but I can't figure out how to get it in, and that's
what I'm using R for.

If you are telling me there is a simpler way to do this, I am all ears
(eyes), especially if it uses grass or qgis which I can afford, and not
Arc, which I can't.

Queries of GIS guys told me that what I need to do is to get my data
into a shape file first and then a GIS can help me display it, so I
turned to R for that.  Was I wrong there, too?

Most of the data I want to map is not currently in any format at all.
It's just numbers I have.  I have shape files for the geography and I
want to apply my numbers to those shapes and draw maps in color, and I
also would very much like to draw the 3d kind where the geographic area
is raised up according to some value.  (I don't know if there's a name
for this.)  I tried to use a spreadsheet to get my data attached to the
shapes, but as soon as I realized I needed to do a join of my data and
the shape file data I began to look for alternatives.

I know that I'm working at a very low level here, but in addition to
Roger's advice before about how to get R to cooperate, I would be
grateful for any advice such as you've provided about what exactly R is
good for in my task and what a GIS is good for.  Your note advances me
down the field quite a bit, but if there's more, I'd be interested to
know it.

Many thanks,

 -tom

My tip is: organize data with spreadsheet and GIS softwares, import (as
shapefile, if possible) in R and make your statistical analysis and
statistical columns of data, export to another shapefile and manipulate the
final map in GIS softwares.

I repeat, it's possible make all these steps in R, and generate great maps,
but the most simple way is above. Personally, I use R to make the final maps
only when I have to produce a long series of simple maps.

I think the best way is the integration of GIS software with R, each one
with his specialty.


King regards,

Raphael Saldanha
BRAZIL
saldanha.plangeo at gmail.com

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-- 
Dan Putler
Sauder School of Business
University of British Columbia

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