Data logger for DS18B20 on Raspberry Pi

import time
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt

names = ("Fenster","Heizung","Gluehbirne","Schreibtisch","RasPi-Prozessor")
mask = (1,1,1,1,1)
file = []
for i in range(5):
    file.insert(i,open("/home/pi/logs/"+names[i]+".csv", 'w'))
    file[i].seek(0,2)
keys = ("28-0415a30daeff", "28-0415a30e46ff", "28-0415a35d77ff", "28-0415a35bd5ff", "28-0415a30f6eff")
times = [[],[],[],[],[]]
data = [[],[],[],[],[]]
start = time.time()
while 1:
    for i in range(5):
        if not mask[i]:
            continue
        ausgabe = open("/sys/bus/w1/devices/"+keys[i]+"/w1_slave").readlines()
        ausgabe[0] = ausgabe[0].split(' ')[11]
        ausgabe[1] = ausgabe[1].split("t=")[1]
        ausgabe[1] = ausgabe[1].rstrip()
        if int(ausgabe[1]) == 85000:
            continue
        if ausgabe[0] == "YES\n":
            file[i].write(str(time.time())+"; "+ausgabe[1]+";\n")
            file[i].flush()
            times[i].append(time.time()-start)
            data[i].append(int(ausgabe[1]))
            print names[i]
            print data[i]
            plt.plot(times[i],data[i])
            plt.xlabel('Zeit ab Start [s]')
            plt.ylabel('Temperatur [mC]')
            plt.title(names[i])
            plt.grid(True)
            plt.savefig("/home/pi/logs/"+names[i]+".png", format="png")
            plt.savefig("/home/pi/logs/"+names[i]+".pdf", format="pdf")
            plt.cla()