AGIS:Programs:Ag

AGIS's AGVIEW v1.0

AGVIEW is an ArcView extension used to display USDA agricultural census data. It is possible to view hundreds of different items. Items can then be saved as dbf or shape files for later use.

Created by David Jones (djones@geog.ucsb.edu at University of California at Davis in conjunction with Zeneca Agricultural Products. Please view legalities.

Ag-View is extremely easy to use.

Running Ag-View.

Open ArcView.
Open the Extension dialog, and check "Ag-View".
Ag-View asks for the cd-rom drive letter. This allows Ag-View to load all necessary data from the cdrom.
Once loaded, a new view is created and the continental United States is displayed.
Under the 'Ag-View' menu, release on Ag-Census Viewer. The viewer pictured below will appear.

Select the year you wish to view.
Select the Table ('Labeled Type') from which you would like to view.
Select the Item from the Table (Labeled 'Item'). The selected item's number will appear in the 'Selected Item #' box.
Before Mapping you must set the legend. This can be done at any time when the viewer is open. Simply Press 'Ag View Legend'. The window below will appear.

First Select a Classification Type. For information on the available types, Consult Arcview's Help.
Now select the type Normalization.
Select the Number of Classes for the color Ramp. The best choice is 13.
Select a color scheme. These are the same color schemes available in Arcview's normal legend editor.
Press Ok.
On the Ag-View Census Viewer control, simply press 'Ag View OK'. In a few moments your selection will be mapped in the view. The selection item and year will be written in the view's title bar. It may look somewhat like this:

You may now dismiss the control or leave it on your screen.

Although certain classifications will include '-1', '-1' is used as the 'No Data' value and will be displayed white. No Data usually means that the USDA didn't record the information. Many times this was because the relevant item was not found in a particular county. So in many cases the null value is the same as a zero value.

Changing years, items and tables.

You can select a new item, and press map at anytime without reselecting all the other options. You can also select a new year and press map without selecting a new item, since it is the same item. Once you have set a legend, it does not need to be changed unless you want to. It can be changed at any time. For the changes to take effect, simply press map again.

Also you can now save data sets to both dbf and shape file's, this is not reflected in the above images. A new ID tool is also included to allow easy id of county information without including useless information to the user.

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Authored by: David Jones djones@geog.ucsb.edu

Please contact Minghua Zhang for general information.

For Minghua Zhang of Zeneca Agricultural Products and the University of California at Davis.

Document prepared July 24^th, 1998

Rewritten: July 24^th, 1998

Help Viewer - David Jones July 1998 - Created with MS VB5

LEGAL:

BY using this product you accept any damage that may occur from either its use, installation or removal. Zeneca, UC Davis and their employees are not responsible for any resulting problems from using this program.

Windows, Windows NT and Visual Basic are trademarks of the Microsoft Corporation, ArcView, Arc/Info and Dialog Designer are trademarks of Environmental Systems Research Institute.