用python绘制cpu曲线

#encoding=utf-8
import  os,time,re
import matplotlib.pyplot as plt
import sys

begin = time.time()
pattern = re.compile("\d+")
time2sleep = 2.5
x = []
y = []
t = 0
totaltime =float(sys.argv[1]) if len(sys.argv)>1 else 10.0
print totaltime
while totaltime>=0:
#    cpuInfo =  os.popen('top -bi -n 2 -d 0.01').read().split('\n\n\n')[1].split('\n')[2]
#    items = pattern.findall(cpuInfo)
#    usage =float(items[0]) +float(items[1])+float(items[2])
#    top巨慢，果断直接从/proc/stat搞起

info1 = os.popen("cat /proc/stat").readline()
ct1 = pattern.findall(info1)
sum1 = 0
for i in ct1:
sum1 += int(i)

time.sleep(0.1)

info2 = os.popen("cat /proc/stat").readline()
ct2 = pattern.findall(info2)
sum2 = 0
for i in ct2:
sum2 += int(i)

usage = (int(ct2[0])+int(ct2[2])-int(ct1[0])-int(ct1[2]))*1.0/(sum2-sum1)*100
print usage,"%"
y.append(usage)

now = time.time()-begin
x.append(now)

totaltime = totaltime - 0.1

end = time.time()

print (end-begin)
plt.plot(x,y)
plt.title("CPU Usage Rate")
plt.xlabel("time/s")
plt.ylabel("percentage/%")

plt.show()