Indexing into a collection (or else) of trials

[eabhorrocks]

I'd like to be able to index into a collection of trials dynamically. It wasn't obvious to me if/how this is possible

Many stimuli are specified by a 'Specification' c# script which allows the generation of a collection of trials with different parameters to be created with the output being a dynamic class (e.g. https://github.com/SaleemLab/VisualStimuli/blob/main/2PStim/DotMotion_SpeedTuning_MatrixRigs_2PRig_FinalLogging.bonsai)

In general we use Concat->(Random)Permutation to generate a random ordering of trials, but I'd like to be able to select the index of the the trial to be presented based on other factors such as what the animal is doing.

For now, I assign different parameters based on an index using expression transform if statements, but this becomes complex if a large number of parameters need to be set (an example is here: https://github.com/SaleemLab/MatrixRigs/blob/main/VisualStimuli/DotMotion_StateDependentSpeed.bonsai).