Efficient way to perform running total in the last 365 day window

Question

This is what my data frame looks like:

library(data.table)

df <- fread(\'
                Name  EventType  Date  SalesAmount RunningTotal Runningt         


        

Answer 1

Using newer non-equi joins feature in data.table:

    df1 = df[.(iName=Name,start = Date - 365L, end = Date),
    on=.(Name=iName,Date >= start, Date <= end),nomatch = 0, allow.cart=TRUE][,
  .(MyTotal = sum(SalesAmount)), by=.(Name,Date = Date.1)]


    df[df1, on = .(Name,Date)]