Group By

group_by() partitions data; combine with iteration for analytics.

Example 036 of the basic Soma programs: a small, commented program that teaches one thing. Every output below was printed by soma 3.2.4 when this page was built.

How it is built

The cell GroupBy has no face and no memory. Handlers: run (line 15).

Generated from soma describe on this file.

The source

036_group_by.cell

// ============================================================================
// 036 — Group By
// ============================================================================
// group_by() partitions data; combine with iteration for analytics.
//
// Run:   soma run 036_group_by.cell run
// Expect:
//   Orders by status:
//     pending: 3 orders
//     shipped: 2 orders
//     delivered: 1 orders

cell GroupBy {

    on run() {
        let orders = list(
            map("id", 1, "status", "pending", "total", 50),
            map("id", 2, "status", "shipped", "total", 75),
            map("id", 3, "status", "pending", "total", 120),
            map("id", 4, "status", "delivered", "total", 30),
            map("id", 5, "status", "shipped", "total", 90),
            map("id", 6, "status", "pending", "total", 45)
        )

        // group_by returns a map where each key is a group and values are lists
        let grouped = group_by(orders, "status")

        // Summarize using agg
        let summary = orders |> agg("status", "total:sum")

        print("Orders by status:")
        for row in summary {
            print("  {row.status}: {row.count} orders")
        }

        return "done"
    }
}

What the toolchain says

$ soma check 036_group_by.cell
✓ All checks passed.

$ soma run 036_group_by.cell run
Orders by status:
  pending: 3 orders
  shipped: 2 orders
  delivered: 1 orders
done