split_axon_dendrite fails for big neurons

[katie-marquand]

If the neuron has too many synapses the geodesic distance matrix can't be initialised because it takes too much memory.

[schlegelp]

Sorry for taking so long. I'm afraid I don't have an immediate fix for this but in the future we should be able to implement something in navis-fastcore that will solve this.

[schlegelp]

Another quick update: I had a crack at this but implemented in rust as part of an experiment in fastcore-rs.

With that I can calculate the synapse flow (which is what failed previously) in ~30s for the hemibrain APL:

(Brighter = higher synapse flow)

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Making an axon-dendrite split based off that currently still needs a bit of tinkering to get to work but if I cut some corners, we get something that doesn't look half bad:

(dark blue = dendrites; cyan = axon)

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I always assumed the APL simply goes calyx (CA) -> peduncle -> lobes but if that skeleton is topologically correct, then the CA + peduncle are actually isolated from the lobes and it's actually CA + peduncle -> lobes.