average_precision_calculator.py 文件源码

def _zero_one_normalize(predictions, epsilon=1e-7):
    """Normalize the predictions to the range between 0.0 and 1.0.

    For some predictions like SVM predictions, we need to normalize them before
    calculate the interpolated average precision. The normalization will not
    change the rank in the original list and thus won't change the average
    precision.

    Args:
      predictions: a numpy 1-D array storing the sparse prediction scores.
      epsilon: a small constant to avoid denominator being zero.

    Returns:
      The normalized prediction.
    """
    denominator = numpy.max(predictions) - numpy.min(predictions)
    ret = (predictions - numpy.min(predictions)) / numpy.max(denominator,
                                                             epsilon)
    return ret