AI and GIS for Beginners
Posted 20 July 2006 - 08:39 PM
In Illustrator (CS2) it takes several hours to fill in each constituency. I take the election results in SPSS and transform them into a number between 0 and 255 to conform to the RGB color scale. Then I take the paintbucket in AI and handfill each constituency. A librarian told me I could use GIS to make this job a lot easier so I purchased a year long student edition of ArcGIS but I can't figure it out at all.
Any advice or step by step hand holding anyone can offer would be much appreciated.
Posted 21 July 2006 - 02:38 AM
For starters you would need the spatial data (the map data) -- which is the administrative regions in Ghana. You can check the admin00 dataset on the "ESRI data & maps" CD that you got with the software (I think), and how good that data is. Otherwise you could look at VMAP0 (from NGA), but their VPF format is not easy to work with.
In the adminstrative regions dataset (whichever you choose) you will see that each region in Ghana has some sort of code, which should be a letter designation or a number.
The next step is to get your election data in order. Work with this in an Access database or an excel sheet (you will need to save to CSV to be able to work with it in Arcmap). Here you need to add a column with the exact same code for the regions that you identified previously.
In ArcMap you now display the regions, and then you create a join (like a database join) to the election data, then those columns will be available for map display as categories (on the symbology tab I think). For this step, you can refer to the help file, look for "join".
For starters -- to learn how to do this -- bring up a dataset (from the above CD) with US states, and get some data (population? statistics?) for the states with the two-letter code, and experiment with joining and displaying it.
Posted 21 July 2006 - 12:26 PM
Like Frax mentioned - first you need some GIS data to load into ArcGIS and you can download data for Ghana here. You might need to look in the HELP for info on importing a compressed format (E00 = Export Interchange file) and use the appropriate tools in ArcGIS.
Then you need to code your data such that you have a unique ID in one column that corresponds to the unique ID from the table associated each constituency in the GIS data. Join your data (I commonly export files from Excel into dbf(iv) format for import into ArcGIS) to the GIS data based on the unique ID's.
To save some yourself some potential anguish you might also ask (hire) someone from your institution to help get things set-up initially for your particular use. It sounds quite interesting.
co-cartographic creator of boringmaps.com
Posted 22 July 2006 - 05:45 AM
Posted 25 July 2006 - 05:15 PM
I take the election results in SPSS and transform them into a number between 0 and 255 to conform to the RGB color scale.
Dootie, you should also learn about data classification. Your above method will not hold water. Check out Slocum's book in the library for more info on a better way to approach this.
Posted 25 July 2006 - 06:23 PM
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