HKUDS/Vibe-Trading · error · ValueError

valuations[{index}] must be a (date, value) pair, got {type(

Error message

valuations[{index}] must be a (date, value) pair, got {type(item).__name__}

What it means

The performance return functions (time_weighted_return, modified_dietz_return, money_weighted_return) normalise a valuations iterable into (date, value) pairs. Each element must be a two-element sequence; passing a bare string/bytes or a non-sequence scalar at some index raises this error naming the index and the offending Python type.

Source

Thrown at agent/src/quantlib/performance.py:308

            ``src.entities.models.normalize_date``, so ISO-8601 strings and
            ``datetime`` instances are accepted.

    Returns:
        Pairs sorted by date, with at least two entries.

    Raises:
        ValueError: If fewer than two valuations were supplied, a pair is
            malformed, a value is not finite, or a date repeats. A repeated
            date is rejected rather than deduplicated because two different
            marks for one day have no defensible ordering.
    """
    if isinstance(valuations, Mapping):
        raw_items: list[tuple[object, object]] = list(valuations.items())
    else:
        raw_items = []
        for index, item in enumerate(valuations):
            if isinstance(item, (str, bytes)) or not isinstance(item, Sequence):
                raise ValueError(
                    f"valuations[{index}] must be a (date, value) pair, got "
                    f"{type(item).__name__}"
                )
            pair = tuple(item)
            if len(pair) != 2:
                raise ValueError(
                    f"valuations[{index}] must have exactly two elements "
                    f"(date, value), got {len(pair)}"
                )
            raw_items.append((pair[0], pair[1]))

    if len(raw_items) < 2:
        raise ValueError(
            "a return needs an opening and a closing valuation; got "
            f"{len(raw_items)}"
        )

    resolved: list[tuple[date, float]] = []

View on GitHub (pinned to 80ffdda44c)

Solutions

1. Build pairs with zip: list(zip(dates, values)).
2. If you meant a mapping input, pass {'2024-01-01': 100.0, ...} which is supported.
3. Validate each element with isinstance(item, (tuple, list)) and len == 2 before calling.

Example fix

# before
twr = time_weighted_return(['2024-01-01', '2024-06-30', '2024-12-31'])  # raises

# after
twr = time_weighted_return([('2024-01-01', 100.0), ('2024-12-31', 105.0)])

vals = list(zip(dates, values))  # ensure pairs before calling
assert all(isinstance(p, (tuple, list)) and len(p) == 2 for p in vals)

from collections.abc import Sequence
def are_date_value_pairs(v) -> bool:
    return all(
        isinstance(i, Sequence) and not isinstance(i, (str, bytes)) and len(tuple(i)) == 2
        for i in v
    )

try:
    r = time_weighted_return(valuations)
except ValueError as e:
    if 'must be a (date, value) pair' in str(e):
        raise DataShapeError('valuations not paired') from e
    raise

When it happens

Trigger: Calling time_weighted_return(['2024-01-01', '2024-12-31']) — a list of date strings instead of pairs; or [date(2024,1,1), 100.0, date(2024,12,31), 105.0] with interleaved flat values; strings are explicitly rejected so they are not expanded character-by-character.

Common situations: Reading a CSV row of alternating dates and values into a flat list; forgetting zip(dates, values); mixing a Mapping for some periods and flat lists for others in user input.

Related errors

• valuations[{index}] must have exactly two elements (date, va
• a return needs an opening and a closing valuation; got {len(
• valuation on {when} must be numeric, got {raw_value!r}
• valuation on {when} must be finite, got {raw_value!r}; a mis
• {model}: {name} must be a finite number, got {val!r}

AI-assisted analysis of HKUDS/Vibe-Trading@80ffdda44c (2026-08-28). Data as JSON: /api/errors/97323f5ae81da216. Report an issue: GitHub.