Analysis of GIS Data by Simple Examination - Introducing Geographic Information Systems with ArcGIS - page 365

LC-CODE LC-TYPE

100 Urban

200 Agriculture

300 Brushland

400 Forest

500 Water

600 Wetlands

700 Barren

7. Open the Landcover attribute table. How many records are in it? ________ So, how many
land cover polygons are there? ________ Sort the table by polygon area by right-clicking the
heading Shape_Area and choosing a sort command. To one decimal place, what is the area of
the largest polygon that is not land cover code 500 (water)? ________ (The units are square
meters.) What is the land cover code of the smallest polygon? ________ What sort of land cover
is it? ________________ If any records or polygons have been selected, press Clear Selection.

8. Calculate statistics on areas: Again right-click the heading Shape_Area, and click Statistics to
get a Statistics of Landcover window. What is the average of the areas of the polygons (to the
nearest tenth of a square meter)? ____________ While you have the statistics window open,
choose Shape_Length in its Field text box. Shape_Length gives the perimeters of the polygons.
If you added the perimeters of all the polygons together what would be the sum? ________
meters. What is the approximate cost per hectare of the most expensive land? $_______
Dismiss the statistics window.

9. Sort the records back into their original order based on the Object Identifier (OBJECTID). Clear
any selections.

Pointing at Records

10. Experiment with various ways of pointing at records: Click any cell of any record. Note
that, in the gray box to the left of the record, a triangular marker appears. The Record
indicator at the bottom indicates the position of that record in the table. By pressing the
buttons on either side of the Record indicator, you can control which record is pointed to.
Only one record may be pointed to at a time. Pointing to records has nothing to do with
selecting records.

Two Windows Are Available for Selecting

As with many operations with this software, there are multiple ways of accomplishing a task. Using the
Selecting by Attributes option is no exception. It's worth taking a look at the two windows you can use
for this. You get to one window through the Options button on an attribute table. You get to the other one
through the Selection menu from the Main menu. As a side trip here, look at both.