python提取log文件内容并画出图表

2016-10-21 21:07:59,787 [7 MainWindowForm]INFO: update time 136.6314
2016-10-21 21:07:59,908 [7 KinectServer]INFO: lClientSockets[0] elapsed time 16.
2016-10-21 21:07:59,918 [7 KinectServer]INFO: lClientSockets[1] elapsed time 107.
2016-10-21 21:07:59,929 [7 MainWindowForm]INFO: update time 135.1311
2016-10-21 21:08:00,039 [7 KinectServer]INFO: lClientSockets[0] elapsed time 14.
2016-10-21 21:08:00,045 [7 KinectServer]INFO: lClientSockets[1] elapsed time 103.
2016-10-21 21:08:00,053 [7 MainWindowForm]INFO: update time 118.1132

import matplotlib.pyplot as plt

input = open('serverlog.txt', 'r')

rangeUpdateTime = [0.0]

for line in input:
  line = line.split()
  if 'update' in line:
    rangeUpdateTime.append(float(line[-1]))

plt.figure('frame time')
plt.subplot(211)
plt.plot(rangeUpdateTime, '.r',)
plt.grid(True)
plt.subplot(212)
plt.plot(rangeUpdateTime)
plt.grid(True)
plt.show()