绘制以日期时间为索引的数据文件，并在python中仅在x轴上显示小时、分钟和秒。

Question

我能够用下面的代码生成以下情节：

df_day['Time'] = pd.to_datetime(df_day['Time'], format = '%H:%M:%S')
df_day = df_day.set_index('Time')

fig=plt.figure(dpi=900)
plt.title("TESTER Summary for Day %i " %y + "\n Average Chamber Pressure %.3f [torr] \n" %p_avg_temp  + str(dates[x]))

ax1 = df_day['DP-2'].plot(label = 'DP-2')
ax2 = df_day['FM-1'].plot(secondary_y = True, label = "Flow Rate")

ax1.set_ylabel('Temperatures - Pressure Drop\nInlet Pressure - Scale Weight')

ax2.set_ylabel('Flow Rate - Heat Rej.')

ax1.set_xlabel('Time ')

handles,labels = [],[]
for ax in fig.axes:
    for h,l in zip(*ax.get_legend_handles_labels()):
        handles.append(h)
        labels.append(l)

plt.legend(handles, labels, loc = 'lower center', bbox_to_anchor = (0.5, -0.5), ncol = 3)
fig.subplots_adjust(bottom = 0.25)

ax1.grid(True, linestyle = ':')
ax2.grid(True, linestyle = ':')
plt.show()

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但我不想让日期出现在xtick标签上。我要几个小时，几分钟，几秒。我也尝试过：

df_day['Time'] = pd.Series([val.time() for val in df_day['Time']])

而不是

df_day['Time'] = pd.to_datetime(df_day['Time'], format = '%H:%M:%S')

但后来我得到了

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时间间隔是任意的，不包括秒数为00的秒。

Answer 1

在编写代码之前，尝试运行以下行：

import matplotlib.dates as mdates

myFmt = mdates.DateFormatter('%H:%M:%S') # here you can format your datetick labels as desired
plt.gca().xaxis.set_major_formatter(myFmt)

看看这篇文章plot_date function set xticks for hourly data