Pulse Documentation

name: op-attr-formula
description: Per-row expression evaluation against the record's fields via expr-lang.
kind: operator
category: ATTR
operator: ATTR_FORMULA
type: reference
applies_to: process, compose, predict
examples_tags: [feature-engineering, streaming-friendly]

Row-level scalars; no Response.Components.

Use when

Adds a number to every row computed from the row’s own fields with an expression, such as price * qty.

Questions it answers:

• What is each order’s line total from its price and quantity?
• Which rows meet a combined rule, as a 0/1 column for counting?

Use something else:

• FILTER_EXPRESSION when you want to keep or drop rows by a rule rather than add a column.
• FEAT_LOG when you want the logarithm of a field.

Params

Inputs

Output

One float64 per record (bools → 1.0 / 0.0); a nil result → null (n_null). Null binds nil: guard x ?? 0 / x == nil ? a : b; unguarded arithmetic on nil → PROCESSING_RUNTIME.

Gotchas

• Reads source fields and EARLIER attribute labels (declared order); stage across requests via Compose / ProcessChain.
• total(expr) (this operator only; lowercase, one argument, no nesting): cohort-wide sum of a row-level expr over post-filter rows — the same figure on every row, also when grouped. Unweighted regardless of Request.Weight; null-argument rows skipped. Empty total → null; zero total as divisor → null. Pro-rata: x * 1000 / total(x). Subset total: x * (1 - 1000 / total(week_index >= 52 ? x : 0)).
• A total formula is two-pass (like the z-score attribute): streams alone, buffers beside groups / features; shard archive, parallel decode and ShardWorkers run sequentially (whole-cohort total); ProcessChain refuses it (PULSE_CHAIN_NOT_MERGEABLE). Predict adds PULSE_ADVISORY_EXTRA_PASS per formula (added_scans).
• Misuse: total() in an expression filter or overlay formula (Compose host too) → PULSE_FORMULA_TOTAL_SITE; nested → _TOTAL_NESTED; arity ≠ 1 → _TOTAL_ARITY. An embedder ExprFunction named total → PULSE_EXTENSION_NAME_RESERVED.
• Compiled once; bad syntax / types → PROCESSING_RUNTIME at build.
• Categorical → STRING (== / in); set_* → []string ("a" in tags, has_any(tags, "a", "b")).
• % on a field: float math.Mod (score % 1, dividend’s sign); % 0 → NaN, as / 0 → ±Inf.

See

• pulse_examples_search tags=[feature-engineering]
• Skills: attribute-composition, expression-language (maths / vector functions, ExprFunctions, lookup(...))