HKUDS/Vibe-Trading · error · ValueError

returns is empty

Error message

returns is empty

What it means

_align refuses empty input: if the (1-D) returns array has zero elements it raises ValueError('returns is empty'). An empty backtest would otherwise produce division-by-zero statistics and empty reports that look like success.

Source

Thrown at agent/src/quantlib/var_backtest.py:291

    if ret_values.ndim > 1:
        raise ValueError(f"returns must be 1-D, got shape {ret_values.shape}")
    ret_values = ret_values.ravel()

    var_values = np.asarray(var, dtype=float)
    if var_values.ndim == 0:
        var_values = np.full(ret_values.shape, float(var_values))
    else:
        if var_values.ndim > 1:
            raise ValueError(f"var must be 1-D or scalar, got shape {var_values.shape}")
        var_values = var_values.ravel()

    if ret_values.size != var_values.size:
        raise ValueError(
            f"returns and var must be the same length, got {ret_values.size} "
            f"and {var_values.size}"
        )
    if ret_values.size == 0:
        raise ValueError("returns is empty")

    keep = np.isfinite(ret_values) & np.isfinite(var_values)
    dropped = int((~keep).sum())
    if not keep.any():
        raise ValueError("no observation has a finite return and a finite var")

    index = ret_index if ret_index is not None else var_index
    kept_index = index[keep] if index is not None else None
    return ret_values[keep], var_values[keep], kept_index, dropped


def violation_indicator(
    returns: pd.Series | np.ndarray | Sequence[float],
    var: pd.Series | np.ndarray | Sequence[float] | float,
) -> np.ndarray:
    """Flag the days on which the realised loss exceeded the VaR forecast.

    Args:

View on GitHub (pinned to 80ffdda44c)

Solutions

1. Debug why the returns array is empty (print its length and index range before the call).
2. Fix date filters / data loading so at least one observation survives.
3. Guard with a length check and skip the backtest when there is no data.

Example fix

# before
var_backtest(returns[returns.index > '2030-01-01'], var)
# after
sub = returns.loc['2024-01-01':'2024-12-31']
if len(sub):
    var_backtest(sub, var.reindex(sub.index))

assert len(returns) > 0, 'no returns in backtest window'

def non_empty(x) -> bool:
    try:
        return len(x) > 0
    except TypeError:
        return False

except ValueError as e:
    if str(e) == 'returns is empty': skip_or_raise_data_error(e)

When it happens

Trigger: Passing [] or an empty Series/array for returns — e.g. a date filter that selects nothing, an empty CSV read, or a test fixture that failed to populate data.

Common situations: Date-range parameters that exclude all rows; upstream API returning an empty payload; empty DataFrame .iloc[:,0] column selection after a bad filter.

Related errors

• brinson_fachler needs at least one sector
• label_end_times is empty
• groups array cannot be empty
• events is empty
• no asset has both a finite value and a positive market cap

AI-assisted analysis of HKUDS/Vibe-Trading@80ffdda44c (2026-08-28). Data as JSON: /api/errors/51dab5b80878daa0. Report an issue: GitHub.