rohitg00/ai-engineering-from-scratch · error · ValueError

probability must be between zero and one

Error message

probability must be between zero and one

What it means

Error "probability must be between zero and one" thrown in rohitg00/ai-engineering-from-scratch.

Source

Thrown at certifications/claude/lessons/26-production-observability-latency-and-cost/code/main.py:34

@dataclass(frozen=True)
class Trace:
    trace_id: str
    variant: str
    duration_ms: int
    input_tokens: int
    output_tokens: int
    cost_usd: float
    task_success: bool
    system_ok: bool
    cache_read: bool = False
    error_category: str | None = None


def percentile(values: list[int], probability: float) -> float:
    if not values:
        return 0.0
    if not 0 <= probability <= 1:
        raise ValueError("probability must be between zero and one")
    ordered = sorted(values)
    rank = max(0, math.ceil(probability * len(ordered)) - 1)
    return float(ordered[rank])


def summarize(traces: list[Trace]) -> dict[str, object]:
    if not traces:
        return {
            "requests": 0,
            "system_success_rate": 0.0,
            "task_success_rate": 0.0,
            "p50_ms": 0.0,
            "p95_ms": 0.0,
            "total_cost_usd": 0.0,
            "cost_per_task_success_usd": None,
            "cache_read_rate": 0.0,
            "errors": {},
        }

View on GitHub (pinned to 39ea8a1c6d)

When it happens

Trigger: Thrown at certifications/claude/lessons/26-production-observability-latency-and-cost/code/main.py:34 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of rohitg00/ai-engineering-from-scratch@39ea8a1c6d (2026-08-26). Data as JSON: /api/errors/db5d185862534776. Report an issue: GitHub.