def ci(arr, conf=0.95):
    """
    Column-wise confidence interval.

    Parameters
    ----------
    arr : array-like

    conf : float
        Confidence interval

    Returns
    -------
    m : array
        column-wise mean
    lower : array
        lower column-wise confidence bound
    upper : array
        upper column-wise confidence bound
    """
    m = arr.mean(axis=0)
    n = len(arr)
    se = arr.std(axis=0) / np.sqrt(n)
    h = se * stats.t._ppf((1 + conf) / 2., n - 1)
    return m, m - h, m + h