Neuropixel units functional metrics

[thewtex]

No description provided.

[brianhhu]

I finished the example notebook. The first example plots the units from each visual area as a point set, only controlling the color of each point set. The second example selects two visual areas and plots each unit as a separate point set, controlling both color and marker size. Unfortunately, the CCFWidget did not render efficiently when I used >60 units, so I had to use a much reduced set of units. I also found the dynamic range of the marker_opacities to be hard to discriminate visually, so I just left them at the default value of 1.