Group by, percentage of total rows?

[vin67]

Apologies I’m very new to observable but I’m stumped and I’m sure its simple for many here.

Is there something similar to pandas group by, aggregate and apply a function to get counts and percentages of total rows?

eg group all rows by school_type, count and create a percentage of the total

df.groupby(‘dem_school_type_by_age_range’).agg({‘dem_school_type_by_age_range’: ‘count’}).apply(lambda x: 100*x/x.sum())

I’ve been looking for a while to figure out in vegalite, the data transform function… or do it inside of observables javascript but I can;t figure it out.

[tomlarkworthy]

d3.rollup(…) is part of the standard library of Observablehq.

d3.group, d3.rollup, d3.index

[tophtucker]

Here’s a notebook showing how to use either Arquero or D3 for this. The Arquero code looks a lot like Pandas:

[vin67]

This is extremely helpful! Very clear. Thank you for taking the time to explain two alternative methods.