IBD Generator

A Rust library for generating Incomplete Block Designs (IBDs) with prohibitions between pairs of treatments. This is a loose port of the optBlock C code from the AlgDesign R package (https://github.com/jvbraun/AlgDesign)

The algorithm creates an optimal design based on D-optimality. For smaller combinations of v, n_b, k, the algorithm should produce a BIBD (if one exists, and presuming no prohibitions of course).

Library Usage

To use the library, you can call the find_best_ibd function with the desired parameters. Here's an example:

let result = find_best_ibd(v, n_b, block_size, n_repeats, iter, prohibited_pairs);

where:

• v is the number of treatments total
• n_b is the number of blocks
• block_size is the number of treatments per block
• n_repeats is the number of repeats per iteration within a single run. Default is 5.
• iter is the number of times the whole process is repeated. For smaller designs (e.g. 7,7,3), the default of 10 is plenty to find the best design. Otherwise - experiment.
• prohibited_pairs is a vector of tuples of usize representing the prohibited pairs. For example, if you want to prohibit the pair (1,2), you would pass vec![(1,2)].

This will generate an IBD with the specified parameters and return the best solution found.

Command Line Usage

The command line interface is a simple wrapper around the ibdgen function.

Usage:

ibdgen 9 12 3 -p "1,2,3,4" --nrepeats 5 --iter 10 

creates an IBD with v=9, n_b=12, k=3 design with prohibited pairs (1,2) and (3,4). --n_repeats and --iter are optional, and default to 5 and 10 respectively.

License

This project is licensed under the GPL3 License - see the LICENSE file for details.

Notes

The code works, but neither my Rust nor my linear algebra are world-class, so doubtless many improvements are possible. In particular, the code is slow for large combos of v, n_b and k given the find_delta_block function which iterates over all pairs of blocks several times.

TODO

• Make the code faster
• Much better error handling. In particular, there are very few bounds checks on input parameters.
• Needs some serious refactoring
• Prohibitions code works but is inefficient.
• Better documentation
• Better tests