SAS Institute has provided ITS/USC with a complete set of
customized TIGER files for use in SAS/GIS under SAS Release 6.12
and later.
These files are accessed with a special Frame, also provided by
SAS for this purpose.
Access to the TIGER files and the 'Tiger-CD' Frame requires
the SAS/GIS Release 6.12 update, a special CD distributed
in Spring 1998 by SAS Institute.
This update has already been applied to the servers providing
SAS for Windows to the ITS
User Rooms, and to SAS for UNIX
running on the RCF and SCF.
Individual users who have current SAS site license copies from ITS
can borrow the CD from the ITS
Customer
Support Center in LVL Lower Commons
(213/740-5555) by appointment.
(Presumably, future releases above 6.12 will include
this software without the need for an update.)
To create a map from the TIGER files provided by SAS:
- Invoke SAS for UNIX in X Mode, or SAS for Windows
(in the User Areas or on a machine where the update
has been applied)
- Enter the following at a SAS Command Line:
AF C=SASHELP.GISIMP.TIGERCD.FRAME
NOTE: If you don't have a Command Line, or don't know where one
is, you can click Globals>Options>Command Line to
request one.
This opens a SAS "Frame"
called the SAS/GIS Map Extraction Utility Window
in which you will
be prompted to enter the path to your 'Tiger CD-ROM'
(this terminology is used in the UNIX environment
and on the User Rooms Windows machines as well,
even though no CD-ROM is needed there).
If you are using SAS for Windows or Macintosh on a system
installed and/or maintained by you, do as requested by
the message SAS gives you.
- In the Map Extraction Utility window, enter the path
to the TIGER map files. In UNIX enter:
/usr/usc/sas/default/TGRMAPS
In SAS for Windows in the ITS User Areas, enter:
g:\programs\stat\saswin\TGRMAPS
Note that, apparently, SAS regards this path as
case sensitive, so TGRMAPS must be all caps.
SAS creates two types of files for GIS work: Map Entries, and
Spatial Data Sets.
You will see these designations in the dialog box where you
specify the State, County and Layer information you want your
map to use.
You may want to accept the defaults, if choices are made for
you, but be aware that SAS creates a number of relatively large
files in GIS work for each map requested, and these could end
up occupying a lot of space.
In general, unless you are familiar with your GIS work and know
which map files you really want to save,
it is a good idea to choose WORK for the LIBRARY field of
each data set type (Map Entries and Spatial Data Sets).
This way, SAS will delete the files used during your GIS session
when your SAS session terminates.
(Often the default is the SASUSER directory, which is not
cleared out automatically at the end of a SAS Session.)
If you do want your map files (or some of them) to be saved
permanently, you can choose SASUSER for the LIBRARY field or
you can use any LIBREF that you have already created
(prior to your SAS/GIS session) using a LIBNAME statement.
The TIGER maps referenced above
are specially compressed and processed by SAS for use
with SAS/GIS through the "TigerCD" Frame.
For this reason, they can be accessed only by the AF
command as shown above, which calls a special access
Frame.
Of course, any appropriate GIS-type maps and data, including the
original TIGER files distributed by the Census Bureau,
can be imported into SAS/GIS using the usual
File>Import menu choices within SAS/GIS.