How to add custom fields? about viz HOT 2 CLOSED

The d3.nest().rollup removes the original data and keeps only the keys and aggregated values.
Examples:
d3.nest().key(d=> d[0]).entries([["A",1,"z"],["B",2,"z"]])

d3.nest().key(d=> d[0]).rollup(d=>d3.sum(d,t=>t[1])).entries([["A",1,"z"],["B",2,"z"]])

A solution could be to replace the nesting step with your own nesting method which keeps the 4th element and then grab it and pass it as a key value in the push step.

from viz.

Thanks NPashaP for your help.

from viz.