Matplotlib pyplot savefig输出显示不同的数据

Question

我有一个循环，可以通过过滤PANDAS数据框来制作大量图表：

def makeChart(name):    
    plt.clf()
    plt.cla()

    filename = "plots/" + name.replace(" ","_")
    series = df[df['name'] == name]
    series_wk = series[['name','start_date','num_nights']].groupby([pd.Grouper(key='start_date', freq='W')]).sum().reset_index()
    series_wk['period'] = series_wk.apply(checkperiod, axis=1)
    series_wk.set_index('start_date',inplace=True)
    series_wk.to_csv(filename + ".csv")

    ne = series_wk[series_wk['period'] == "Non-election"]
    e = series_wk[series_wk['period'] == "Election"]

    fig, ax = plt.subplots(figsize=(15,7))
    ax.bar(ne.index, ne['num_nights'], color='b')
    ax.bar(e.index, e['num_nights'], color='r')
    ax.xaxis.set_major_locator(ticker.MultipleLocator(50))
    ax.xaxis.set_major_formatter(mdates.DateFormatter('%d-%m-%Y'))
    ax.set_title(name)
    plt.xticks(rotation=90)
    fig.savefig(filename)
    plt.show()

makeChart("CARR Kim")

plt.show（）的输出具有正确的数据，并且looks like this 但是，保存的文件中的数据和looks like this不正确。 我是使用matplotlib的新手，实际上无法弄清楚为什么实际数据点在这里会有所不同。任何帮助将不胜感激！