Analysis of GIS Data by Simple Examination - Introducing Geographic Information Systems with ArcGIS - page 397

road, maybe we can get a few more census blocks by looking at two circles, centered at opposite ends of
the road. (If this doesn't work, we might be able to argue that while our first method overestimated the
population, the current one probably underestimates it.)
43. Click the circle with the Select Elements tool. Press the Delete key to make it go away. Under
Selection click Clear Selected Features. If you made the roads layer un-selectable make it
selectable again. Select the Galbraith School Road segments again (the formula may still be in
the Select box) and zoom to leave about 5 miles all the way around them. Click the circle icon
on the Drawing toolbar and again draw a 3.00 mile radius circle, but center it on the southeast
end of the road. Then, click the circle icon again and drag a second 3.00 mile circle centered
on the northwest end. Pick the Select Elements tool. Hold down Ctrl and click within each circle
so that both are selected. Under the Selection menu pick Select By Graphics, click OK, and
wait. The boundaries of the selected blocks should appear shortly.
44. Now open the Blocks&Pop_TN_SP attribute table. How many records are selected? ________.
Run statistics on P001001 in the selected records. What is the population within the blocks
that fall completely inside the pair of 3-mile circles? ____________. Call the banker back!
45. Close ArcMap, saving the map as Day_Care_YES.mxd in Day_Care_Data.
Exercise 6-5
Determining Proximity of Points to Lines and Other Points
For this exercise, we return to our fictional islands of Chapter 5. You may recall that you digitized them in
___IGIS-Arc_ YourInitials \Digitize&Transform
\Islands.mdb\UTM_Zone_2
The data set became North_Islands_Polys. You stored a map named North_Islands_map3. Houses are
being built on the square island. A power generation plant is being constructed on the northwest corner of
the lake and a power line run from the plant around the island. Also, wells are being dug to supply water
to the houses. These feature classes are called Houses, Power_Lines, and Wells. In order to bring the
appropriate lengths of electrical wire and water pipe to the island, we want to know the distances from the
houses to the power lines and the distance from the houses to the wells. This information will be stored in
the attribute table of the Houses feature class.
1. Start ArcCatalog. From
[__] IGIS-Arc_AUX\D&T\Islands.mdb\UTM_Zone_2
copy the PGDBFC named Power_Lines to
___IGIS-Arc_ YourInitials \Digitize&Transform
\Islands.mdb
Now also copy the feature classes Houses and Wells. Close ArcCatalog.