I have recently written a Python script, called "Flowpy", to replace the functionality of the Flow Data Model Tools. I have not created any formal documentation for Flowpy yet, but the following comments may be sufficient to get things working. The script is much faster, is less error prone, and does not rely on ArcGIS to operate. However, the code does require Python 2.6 and GDAL; both are free and open-source. Instructions to get GDAL and Python installed and working can be found here: http://ucsb.pbworks.com/Using-GDAL-with-Python.
Flowpy is available at: http://www.enj.com/software/index.php. The script uses an interaction matrix file and corresponding coordinate pair file, calculates gross, net, or two-way flow from them, and yields a shapefile. To run Flowpy, you'll need the two script files: "flowpyInterface.py" and "flowpyv07.py". On the download page, these files end with the suffix .txt. Once the files are downloaded, replace the .txt with .py so your computer will realize they are Python scripts. You will also need two data files, a text file of point coordinates and a text file interaction matrix. Concerning the file specifications for the data files, the coordinate pair file should be one coordinate pair per line and the x y coordinates must be space delimited. The interaction file requires a square space delimited matrix of magnitude values. Each row refers to a "from" node; each column refers to a "to" node. In the following file examples, flow from row 3 (node 3: coordinates -75 40), column 11 (node 11: -96.75 32.75)coordinates possesses the value 10.
Example formatted coordinate pair data:
--------------------------------------------------------------------------------------------------
-71 42
-74 41
-75 40
-81 41
-77 37
-84 33
-88 42
-90 39
-93 45
-94.5 39
-96.75 32.75
-122.5 37.75
--------------------------------------------------------------------------------------------------
Example corresponding formatted interaction matrix:
--------------------------------------------------------------------------------------------------
2040 289 47 52 137 118 90 10 16 15 13 80
602 1980 231 209 388 307 286 15 48 26 18 261
143 414 860 84 342 130 134 8 25 10 10 80
68 192 47 1296 171 177 618 16 44 43 19 131
150 266 158 226 3899 578 295 20 62 54 22 152
122 159 57 186 319 3741 439 30 51 78 102 189
97 155 39 496 143 266 5630 74 278 100 40 290
31 56 14 142 80 201 573 342 46 128 47 109
14 26 11 32 29 41 295 10 1438 51 14 138
20 41 8 55 40 71 215 33 129 811 86 247
31 41 8 38 46 165 125 20 37 253 788 203
82 81 23 84 114 106 251 22 127 128 43 5380
--------------------------------------------------------------------------------------------------
To make Flowpy work, edit FlowpyInterface.py to include your own variables and filenames as appropriate and then execute FlowpyInterface. The code is documented well enough to make pretty good guesses of the names to change. When the FlowpyInterface script runs, it passes the variables over to Flowpy07. Otherwise, Flowpy07 can be run independently from the Python command line, but that is a little more advanced.
Eventually I'll write more formal doc and/or a video demo. Hope this helps.
Regards,
Alan Glennon
UCSB Geography