Working with Vam Files in G7

G7 is part of the Interdyme software for building dynamic interindustry models. These models store their vector and matrix data in files called Vam (for Vectors And Matrices) files. Usually a model has a single Vam file that contains all vectors and matrices used in that model. To speed reading and writing during the execution of the model, these files are organized quite differently than the usual G7 data bank. The usual bank places the data for successive observations on a single variable in adjacent memory positions. The Vam file, on the contrary, organizes all of the cells of a vector for one year before going on to the next year. This difference largely is transparent to the user of G7, but it explains why some ways of working are faster than others.

VAM files can be created and viewed in G7 and used as a source of data for regression or graphing. They are just another type of data bank as far as G7 is concerned. Several Vam files can be attached at the same time and use as sources of data. Data input and manipulation, however, is possible in only one Vam file at a time; this one is called the default Vam file. The next sections explain how to create a Vam file, how to make it the default Vam file, how to load data into it, and how to transform it in several ways.

G7 can create and manage Vam banks at annual, quarterly, and monthly frequencies. At this time, the other model building programs support only annual frequency for Vam files. These other programs include IdBuild, Fixer, MacFixer, Compare, and the InterDyme C++ library.