Plot a small (mini) histogram of the data.

    Parameters
    ----------
    series: Series
        The data to plot.

    Returns
    -------
    str
        The resulting image encoded as a string.

def mini_histogram(series, **kwargs):
    """Plot a small (mini) histogram of the data.

    Parameters
    ----------
    series: Series
        The data to plot.

    Returns
    -------
    str
        The resulting image encoded as a string.
    """
    imgdata = BytesIO()
    plot = _plot_histogram(series, figsize=(2, 0.75), **kwargs)
    plot.axes.get_yaxis().set_visible(False)

    if LooseVersion(matplotlib.__version__) <= '1.5.9':
        plot.set_axis_bgcolor("w")
    else:
        plot.set_facecolor("w")

    xticks = plot.xaxis.get_major_ticks()
    for tick in xticks[1:-1]:
        tick.set_visible(False)
        tick.label.set_visible(False)
    for tick in (xticks[0], xticks[-1]):
        tick.label.set_fontsize(8)
    plot.figure.subplots_adjust(left=0.15, right=0.85, top=1, bottom=0.35, wspace=0, hspace=0)
    plot.figure.savefig(imgdata)
    imgdata.seek(0)
    result_string = 'data:image/png;base64,' + quote(base64.b64encode(imgdata.getvalue()))
    plt.close(plot.figure)
    return result_string