ArcView your data

First, get you up and running in ArcView, and have you load in some of their data (US counties). A query will get you to a data set containing only the Illinois counties.

We will then add in additional data layers: both the data you downloaded last time for Illinois counties, plus some of Geoff Jacquez's Illinois cancer data. You will choose one data set (there are 30 cancers or so), although if you finish early, you are welcome to do more.

Finally, you will carry out some of the elementary analyses discussed in the last lecture, including overlays and buffering, and print your resulting map.

Getting Started: IL Counties

• Run ArcView.

  Umich students: on the lab computers this is done from the Start menu as follows:
  Start -> Course Software -> Snre -> ArcView 3.1 -> ArcView GIS Version 3.1.

• ArcView may ask if you want to create a New Project (with a new view). Why not?

  As you create a new project, notice the window that is in the background. This window (called "Untitled" by default) we will call the Project window. As soon as you have accepted to create a new project, you will also have a View Window.

• ArcView will then ask if you would like to add data to the view now: again, accept their charitable offer.

  By doing so you indicate that you now want to add a theme (this means view a data layer, or data set). The data set you will want to select is one that is provided by ESRI, and so is found from a directory containing their data sets: esri -> esridata -> usa -> counties.shp.

• Having selected this data set, ArcView produces nothing in the view, but to the left in the View Window you see the name "counties.shp", with an unchecked check-box, and color patches. Click on the check-box.

• A map of the USA appears, with all the counties drawn in. This is an example of a map of vector data, where the vectors determine a set of areas (polygons), rather than strictly linear features.

  Click on a county in the map. By default, you should be in "info mode" (the little "i" in your cursor tells you that you're in info mode), so it will tell you where you are, what's there, etc. (Notice the FIPS code, mentioned in an earlier module.) You are performing a Query, and discovering that the areas have attributes associated with them, which are reported each time you click on an area.

• Under the Window menu item, try switching between Cascade and Tile modes (just for fun).

• Since we ultimately want to focus on the state of Illinois, you will want to zoom in. On the menu bar you see the magnifying glass with a plus sign:
  
  Click that, and you're in zoom mode. Note the difference between clicking on a spot, and dragging the left mouse over an area (creating a new viewing rectangle). Try the "zoom out" mode too (minus sign). In the end, zoom in on Illinois.

• Now we want to do a selection: we want to select only those counties of Illinois. This time you will construct a query, by clicking on the hammer icon
  
  (where do they get these icons?? I guess hammers are associated with construction. Of course!).

  We want those counties in Illinois, so one way to do the Query is to double click on State_name, then, when State_name appears in the query builder box below, click on the equal sign, double click on "Illinois", then click on "New Set". Here's what the query looks like.

  Under the View menu item, you can click on "Zoom to selected", and Illinois appears, as if by magic.

• Now convert your new theme (counties of Illinois) to a shapefile (that is, we want to create a new file which contains only these counties). Go to the Theme menu item, and select "Convert to Shapefile". You'll want to save the resulting shapefile (call it illco.shp, to stay consistent with this lab) to the illinois directory in your account (which you recently created as a subdirectory of the data directory you created in the last module when you downloaded the Illinois census data - if you didn't yet download the data, then please do! Return to the first module's lab and follow directions). Go ahead and add the shapefile to your current View (it will ask you if you want to - of course you do!).

• Now that you have Illinois counties, you can get rid of the other theme (counties). Click on the legend of the counties.shp theme (making it the "active" theme). This will bring that theme button forward. Go to the Edit menu item, selecting Delete Theme (you are not deleting files, only removing "themes" from the project - you can get the county map back any time you'd like, by just following the directions above).

• At this point you should save your project, as you've done some meaningful work on it. Under the File menu item, you'll find "Save Project". Again, save this project to your account area. If you now look in your illinois directory, you will see some new files, including a .dbf (dBase file) which contains the attributes of the Illinois counties.

• Go get a drink of water: you deserve it.

The Attribute table

• Have a look at the attribute table associated with this vector map theme. To do that, click on the legend (note that many buttons become active once you do that). Click on the Theme menu, selecting Table. This should produce a small spreadsheet of your theme's attributes.

• If you double click on the legend of your view there are several options with which you may want to experiment. Change the classification field from Single Symbol to Graduated Color. Classify by 1990 Population, normalizing by the 1997 population value, and click the Apply button. What conclusions can you draw from this choropleth map?

Joining and adding tables

1. one is disease data (by county);
2. the other is a site file containing the locations of the nuclear power plants (which bear no particular relation to the counties).

In the case of the nuclear sites, we are simply adding an additional point data set (or point theme) to the project, which can be overlaid on the vector county theme. Here are the steps:

• You will now get one set of the disease (cancer) data and save it to your illinois directory. Here's a list of the available cancers: pick one and remember its number.

  Disease data is in ASCII format. There are thirty cancers (this is the same data used in Geoff Jacquez's article). Choose your cancer file (the .txt file, e.g. il01wm.txt for lip cancer in white males) from this directory.

  Spend a minute just examining your file. Note the (modest!) amount of meta data at the top of each file. If you see any -9.000 values in your file (e.g. il01wm.txt), can you guess what -9.000 stands for?

  In case you're interested, have a look at an example of the raw data, in the DAT formats (Yuck!). When downloading data from across the internet, or receiving data from a colleague, it often arrives in a format which must be processed before you can use it in your software. This may be extremely painful at times....

• You will need to edit this ASCII disease data file to conform to ArcView's import facility.
  You can do this in any word processer you want (e.g. Notepad, Word), but make sure that you save the result as ASCII text (and use the .txt extension). For this reason you may want to consider using Notepad: it saves everything in ASCII. You will see that your cancer data is in six columns. ArcView expects the data to be delimited (that is, the columns should be separated) with either commas or tabs, and to have a single line at the top of the file (delimited in the same way) which indicates the name of each column's variable. You can use whatever names you like for these variables.

  To save you all a lot of pain, I've already tab delimited the files. They weren't originally tab delimited. I've left you the remainder of the pain. Good luck. The tasks are thus to

  • remove the 5 lines of meta data at the top of the file,
  • add a single tab delimited (tab separated) list of six variable names, e.g.

    latd    latm    longd   longm   Lip_cancer_rate FIPS
    

    as the first line, and
  • save the result as an ascii file.

• Once you're ready with your file, you will click on the Table icon
  
  in the Project window (activating the table menu items). Under the Project menu, you see Add Table, which is precisely what we want to do. Let's start with the cancer data file file. You'll want to import in text (rather than dbf) format.

  Once you've imported the table, you'll see that it has been added to the list of tables.

• We will now join the cancer data to the attribute table of the illco theme: that is, we want to add the attributes in the cancer data to the attributes that ESRI saw fit to provide with the county areas. You need to
  • open both tables (the cancer data and the attribute table);
  • Start with the cancer file (the order is important!): click on the column name you gave to the FIPS column in this file (we will join the files using this column), then
  • click on the column name of the attribute file's FIPS code (the 5 digit code). Again, you should be looking at two columns containing the same type of information: if not, they won't match up, so you'll join nothing!
  • The little "seat belt" icon (join!) should be illuminated in the menu at the top: click on it, and you see that the attribute file has just grown by the columns in the cancer data set: the cancer data has been joined to the attribute table.
  • Now if you go back in and fiddle with the legend, you will see that you can plot other choropleth maps, based on the new cancer data.

• Save the nuclear power plant data (ilnukes.txt) to your illinois directory, then load it into ArcView, following the same Add Table procedure. This time, however we don't want to do a join: there's nothing to join the nuke data to! No place to hang a hat on counties.

• Load in the data you downloaded last time (the county(a/b).csv data - both files), using the Add Table option from the Project menu. This file is delimited in a different way, with commas, but ArcView will know what to do so long as you specify text format (although it will not show the file, because its name does not end in .txt or .dbf - you will have to type in its name, e.g. countya.csv). This data too can be joined to the attribute table (remember: order of the join matters: do the target second). Your attribute file should be getting pretty big!

  Adding Sites to your view

• Click on your view to make it active. To now add these nuclear power plants to your view as site data, you'll need to "add an event theme". This is done from the View menu at the top. Add the countya file and the nuclear sites file as event themes. (Note: countyb can't be added as an event theme as-is, because it doesn't contain the lat-long coordinates (those are in countya.csv). If you wanted to include it with the point theme, you could first join the two county tables.)

  Once you add them, you'll know what to do: display them first (effectively creating an overlay of data layers), and then play with their legends. You can now add the nuclear sites to your "analysis" of cancer.

Buffering

• From the View menu, choose Properties, and set the distance units to miles.

• Click on the legend of the event theme associated with countya, to make it active.

• From the Theme menu, choose Select by Theme.

• A dialog box appears. You'll want to choose the relationship "Are within distance of", choose the nuclear site theme, and put in 60 miles for the distance. Hit new set, and away you go!

• The selected sites can be identified from the table.

• Now create a "layout" for your map. With the view window active, select "Layout" from the options available from the "View" menu item on the top menu bar. Make your layout full screen, edit it (change the title, for example, by clicking on it), and make a pretty (perhaps even useful) map. Print it out when you're done.

  Umich students: when the print dialog comes up, use Native OS rather than ArcView Enhance or ArcView Basic for the print. Write a brief interpretation and hand it in. Geoff would like these, just for fun. Don't sweat it, but do your best. Label it with Cancer type (we don't need your name, unless you're feeling proud of the result).

If you're feeling adventurous...

• Try some additional queries. In which counties are there fewer then 500 10 to 13 year olds?

• Add additional ESRI data themes (e.g. rivers, from the same directory as the counties.shp file).

• you may want to return to the ftp site for the census data and pull down some of the place information (e.g. placea): this is site data for cities and towns in Illinois, also in .csv file format (it's big: about a meg when uncompressed).

• Get a start on digitizing (we'll do this in a later module).