Geography 4050 / 8056

 Geographic Information Systems

 Dr. Michael Peterson

 DSC 264 (through 260); 554-4805


Joining Data to Maps with ArcMap


Steps for downloading a map and a data file.

Getting Data:

  1. Go back to the GIS default page and right click on the Download Election Map link
  2. Choose Save Target As and save the file as a zip file named Omaha_94.
  3. Also,  right click on the Download Election Data link
  4. Save this file and name it 94electiondata (this file is a dbf file).

Unzipping the ZIP file:

  1. Go to the Start menu in the bottom left-hand corner of the screen
  2. Go to Programs, then to EnZip.
  3. Click on File and Open Archive.
  4. Navigate to where you saved
  5. Double click on
  6. Choose the extract icon (fourth icon from the left that looks like a folder)
  7. Keep the name Omaha_94 and click on extract.

Now you have a file and folder, both named Omaha_94

Opening ArcMap:

  1. Click on the Start menu
  2. Go to Programs, then to ArcGIS and open ArcMap.

Adding data...

  1. Select create A new empty map and click OK.
  2. Click on the Add Data button to add data.
  3. Navigate to where you saved Omaha_94 and double click on it.
  4. Double click on Polygon.
  5. An error massage might come up. Click OK. Now a map of Omaha should appear in the right window.
  6. This is a good time to save your project.  Under File, go to Save As... and save this project as ArcMap2.mxd.

Joining Data to maps:

  1. The next step is to join an external data table with your shapefile. This can be done when the data in the tables has a on-to-one relationship. This means that one attribute row in both tables has to be the same.
  2. To first import the data table click the Add Data button, navigate to where you saved the 94electiondata.dbf and click Add.
  3. This should automatically add a table symbol with the name 94eclectiondata.dbf underneath your Omaha_94.shp layer.
  4. To now join this table to the Omaha_94 shapefile right-click on the Omaha_94.shp layer, point to Joins and Relates, and click Join.
  5. In the Join Data which opens click the first dropdown arrow and click Join attributes from a table.
  6. Click the second dropdown arrow and click the field name in the layer on which the join will be based (CODE).
  7. Click the third dropdown arrow to choose the table to join to the layer (94electiondata).
  8. Click the fourth dropdown arrow and click the field in the table on which to base the join (WARD_PREC).
  9. The CODE column in the shapefile table and the WARD_PREC column in the 94electiondata both index the other attributes available.
  10. Click OK.
  11. The attributes of the 94electiondata.dbf are now appended to the Omaha_94.shp layer's table.
  12. Double click on the Omaha_94.shp, this will bring up the Layer Properties window. Choose the Symbology tab and click Quantities. Choose graduated color, then select the Value to one of the four candidates that you would like to map. There will be a lot of choices, the four that you need are Kerry, Stoney, Hoagland, and Christensen, choose one. Next select a color scheme that you want. (To get a color scheme click on the color ramps, choose a color and click apply)
  13. Also, create a map that compares a democratic vs. a republican candidate. Map out one candidate and make two classes with the break at 50%. Numbers over 50% indicate where the candidate you mapped out won, votes under 50% count for the opposite candidate.
  14. The title of the legend must now be changed. Double click on the Omaha_94.shp, move to the General tab, highlight the Layer Name and change it to something relevant to the map with the appropriate candidate's name and click ok.
  15. SAVE your project again by selecting save in the file menu.

Creating and organizing a Layout...

  1. Under the View window, select Layout View.  Create a Layout based on the descriptions of exercise 1 (Omaha Census).

Saving the file:

  1. Once you are happy with the layout, select File-Export Map to save the map to pdf. Name your file accordingly.
  2. Submit the map to your web server folder as ker.pdf, ston.pfd, hoag.pdf, or chris.pdf.

  Updated by Kristie Raymond, 9/9/02, further updated by Eva Grund, May 2005.