def _equally_weight_samples(samples, weights):
    """ Convert samples to be equally weighted.

    Samples are trimmed by discarding samples in accordance with a probability
    determined by the corresponding weight.

    This function has assumed you have normalised the weights properly.
    If in doubt, convert weights via: `weights /= weights.max()`

    Parameters
    ----------
    samples: array-like
        Samples to trim.

    weights: array-like
        Weights to trim by.

    Returns
    -------
    1D numpy.array:
        Equally weighted sample array. `shape=(len(samples))`
    """
    if len(weights) != len(samples):
        raise ValueError("len(weights) = %i != len(samples) = %i" %
                         (len(weights), len(samples)))

    if numpy.logical_or(weights < 0, weights > 1).any():
        raise ValueError("weights must have probability between 0 and 1")

    weights = numpy.array(weights)
    samples = numpy.array(samples)

    state = numpy.random.get_state()

    numpy.random.seed(1)
    n = len(weights)
    choices = numpy.random.rand(n) < weights

    new_samples = samples[choices]

    numpy.random.set_state(state)

    return new_samples.copy()