Window columns

Window columns are extra, read-only measure columns the engine derives by looking across a node’s siblings: a cumulative running total, a 1-based rank, a share of the total or of the parent, a delta versus the previous sibling, or a trailing moving average. They are declared, not hand-computed — the engine (or the parity-verified core port) does the math, and each appears as one more column after your base measures.

This is best seen in a running app; the derived columns append to the same roll-up tree. The declarative config is the star here:

Dash (Python)

from dash_tensor_grid import TensorGrid, build_grid

payload = build_grid(sales, {
    "rows": ["region", "country"],
    "measures": {"revenue": "sum"},
    "formats": {"revenue": "currency:USD"},
    "window_columns": [
        {"kind": "running_total", "by": "revenue", "as": "cum", "format": "currency:USD"},
        {"kind": "rank",          "by": "revenue", "as": "rev_rank"},
        {"kind": "pct_of_total",  "by": "revenue"},   # -> revenue_pct (percentage:1)
        {"kind": "pct_of_parent", "by": "revenue"},   # -> revenue_pct_parent
        {"kind": "delta",         "by": "revenue"},   # change vs previous sibling
        {"kind": "ma",            "by": "revenue", "window": 3},  # trailing 3-period average
    ],
})
TensorGrid(id="grid", row_data=payload["row_data"], column_defs=payload["column_defs"])

React

<TensorGrid
  data={data}
  rows={['region', 'country']}
  measures={{ revenue: 'sum' }}
  formats={{ revenue: '$0,0' }}
  windowColumns={[
    { kind: 'runningTotal', by: 'revenue', as: 'cum', format: '$0,0' },
    { kind: 'rank', by: 'revenue', as: 'rev_rank' },
    { kind: 'pctOfTotal', by: 'revenue', as: 'rev_share', format: '0.0%' },
    { kind: 'pctOfParent', by: 'revenue', as: 'rev_of_parent', format: '0.0%' },
    { kind: 'delta', by: 'revenue', as: 'rev_delta' },
    { kind: 'movingAverage', by: 'revenue', as: 'rev_ma3', window: 3 },
  ]}
/>;

Vue

<TensorGrid
  :data="data"
  :rows="['region', 'country']"
  :measures="{ revenue: 'sum' }"
  :formats="{ revenue: '$0,0' }"
  :window-columns="[
    { kind: 'runningTotal', by: 'revenue', as: 'cum', format: '$0,0' },
    { kind: 'rank', by: 'revenue', as: 'rev_rank' },
    { kind: 'pctOfTotal', by: 'revenue', as: 'rev_share', format: '0.0%' },
    { kind: 'delta', by: 'revenue', as: 'rev_delta' },
    { kind: 'movingAverage', by: 'revenue', as: 'rev_ma3', window: 3 },
  ]"
/>

Vanilla JS

mountTensorGrid(el, {
  data,
  rows: ['region', 'country'],
  measures: { revenue: 'sum' },
  formats: { revenue: '$0,0' },
  windowColumns: [
    { kind: 'runningTotal', by: 'revenue', as: 'cum', format: '$0,0' },
    { kind: 'rank', by: 'revenue', as: 'rev_rank' },
    { kind: 'pctOfTotal', by: 'revenue', as: 'rev_share', format: '0.0%' },
    { kind: 'delta', by: 'revenue', as: 'rev_delta' },
    { kind: 'movingAverage', by: 'revenue', as: 'rev_ma3', window: 3 },
  ],
});

Options

• kind — one of running_total, rank, pct_of_total, pct_of_parent, delta, ma (Dash config, matched case- and underscore-insensitively) / runningTotal, rank, pctOfTotal, pctOfParent, delta, movingAverage (JS adapters).
• by is the base measure to derive from; as names the derived column (each kind has a sensible default key when omitted in the config).
• rank takes descending (default true) and dense; delta takes percent: true for a percent change; ma / movingAverage takes window (default 3).
• Percent kinds store a fraction in [0, 1]. In the Dash config they default to percentage:1; in the JS adapters give a % number format ('0.0%').
• Window columns apply to the row tree only — they are refused on a pivot config. Pair them with a top-N roll-up to rank-and-cap in one pass.