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differencing aggregates in dataview #3235

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differencing aggregates in dataview#3235

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@rustyconover
rustyconover
opened on Sep 21, 2026

Hi Perspective Team,

I've been using the Datagrid for a bit and what would be really useful for me is to be able to calculate differences across aggregate columns that are split.

My specific fictional example:

I have a dataset that has pnl per portfolio per day that accrues. The pnl column doesn't start a zero every day.

In the data view I split that dataset by day, but I want to be able to see for each portfolio how much the PnL changed per day. This involves a lag() operator in SQL, but I'm not sure how to express it in the builder. Is this even possible?

I know I could go hack my data source but it is so much easier to use Perspective.

Thanks,

Rusty

Activity

  1. texodus commented on Sep 21, 2026

    @texodus
    texodus
    on Sep 21, 2026
    Member

    I believe what you describe can be implemented using >5.1.0 window columns, something like this in JSON:

    {
  "group_by": ["portfolio"],
  "split_by": ["day"],
  "columns: ["pnl", "chg"],
  "aggregates": { "pnl": "last", "chg": "sum" },
  "windows": {
    "chg": { 
      "column": "pnl", 
      "aggregate": "diff",
      "partition_by": ["portfolio"],
      "order_by": ["ts", "asc"] 
    },
  },
}

    Also potentially related (which I am currently working on) #3198 #2685

    (converting to a discussion)

  2. perspective-dev
    locked and limited conversation to collaborators on Sep 21, 2026
  3. texodus
    converted this issue into a discussion #3236 on Sep 21, 2026
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