Update: I fixed a mistake on how I was calculating R0 (I think it's correct now) and also adding some basic smoothing with moving average options.

With this approach the R0 estimations are always lagging, so the most recent estimate I have for NYC is for 4/4/2020 with an R0 hovering right around 1.0 - at that date growth was steady linear.

As new data on fatalities comes in, hopefully will see this decrease.