我正在尝试运行一个Python脚本，用于长期实验室数据采集（约1个月）。下面的脚本应该从SQL数据库中获取数据并从DAQ设备获取数据并将其保存到文本文件中。然后它实时绘制1小时的数据。实时绘图已被注释掉，因为我已经得到了内存错误，但这不是我关心的问题。
运行代码3-4天会给我以下错误：
Trackback (most recent call last):
file *** line 105 in <module>
deltay=float(float(tupline[3]/10-float(tupline2[3])/10)
TypeError: 'NoneType' object has to attribute '__getitem__'
关于如何让这个脚本运行更长时间的任何想法？
import ctypes
from UniversalLibrary import *
import time
import datetime
from numpy import *
from scipy import *
import MySQLdb as mdb
import matplotlib
matplotlib.use('Agg')
import matplotlib.pyplot as plt
import random
boardNum=0
portNum=10
inputVoltage = 3
BoardNum = 0
Gain = BIP5VOLTS
Chan = 0
spTimes =14*24*60*60 ##here you set the time
timeDuration=spTimes
padsToVisualize =[0,1,2,3,4] ##pads that will be measured and visualized
#plt.ion() ##this command is necassary in order to have new points on the plot without erasing the old ones
curTime=time.clock()
movingWinDur=60 ##seconds
print "curtime=",curTime
str_one_line=[]
straverage=[]
while (curTime < timeDuration):
del str_one_line[:]
padCounter=0;
d=datetime.datetime.now()
str_one_line=[(d.strftime("%Y-%m-%d %H:%M:%S")),','] ##formatting the date -- this format is chosen based on the requirements for connecting to SQL database
while (padCounter <len(padsToVisualize)):
#fig1=plt.figure(padsToVisualize[padCounter]) ## making figures for plotting different pads
print "pad No.: ", str(padsToVisualize[padCounter])
#l=cbAOut(BoardNum,Chan,Gain,3019) ## sets the voltage to 3.0 volts (the number 3019 is based on 12-bit resolution --> DAQ resolution)
#n=cbDConfigPort(BoardNum,portNum,1) ##the variable n serves aas a command line where the command is sent to the DAQ
#b=cbDOut(BoardNum,portNum,(63-padsToVisualize[padCounter])) #####based on Prof. Mayer's solution, the line sends the pad number that we are interested in to the DAQ to get the signals
curTime=time.clock()
d=datetime.datetime.now()
#########################################################################
########## this part will use the datetime to fetch the temperature from the SQL data base
########## since the time stamps may not exactly match, the code uses a method of interpolation
freq = 5
time.sleep(1.8*freq) ## 1.8 is an arbitrary number ; to make sure there is data on sql database
searchfor=d ## the following lines find the temperature at time=searchfor
print searchfor
minussearchfor = searchfor-datetime.timedelta(0,freq/1.2)
STRminussearchfor = minussearchfor.strftime("%Y-%m-%d %H:%M:%S")
print "STRminussearchfor=", STRminussearchfor
print "minussearchfor= ", minussearchfor
plussearchfor =searchfor+datetime.timedelta(0,freq/1.2)
print "plussearchfor= ", plussearchfor
STRplussearchfor = plussearchfor.strftime("%Y-%m-%d %H:%M:%S")
print "STRplussearchfor=", STRplussearchfor
##Database connection
db = mdb.connect("localhost", "root", "qwerty@12345", "bondtest")
cur = db.cursor()
cur.execute("SELECT * FROM bondtest_data WHERE DateTime BETWEEN %(date1)s AND %(date2)s ORDER BY DateTime",{'date1':STRminussearchfor,'date2':STRplussearchfor})
## con=pymssql.connect(host='LAB10-PC\SQLEXPRESS2008R2',user='sa',password='qwerty@12345')
## cur = con.cursor()
## cur.execute('SELECT * FROM OVEN11SQL.dbo.OvenLog1 WHERE DateTime BETWEEN %(date1)s AND %(date2)s ORDER BY DateTime',{'date1':STRminussearchfor,'date2':STRplussearchfor})
tupline1 = cur.fetchone()
## print 'between1= ',tupline1[1]
delta = tupline1[1]-searchfor
## print "delta = " ,delta
if (int(searchfor.strftime("%S"))-int(tupline1[1].strftime("%S"))>0):
delta = int(searchfor.strftime("%S"))-int(tupline1[1].strftime("%S"))
else:
delta = int(tupline1[1].strftime("%S"))-int(searchfor.strftime("%S"))
## print 'delta= ',delta
time1=tupline1[1]-datetime.timedelta(0,freq/1.2)
STRtime1=time1.strftime("%Y-%m-%d %H:%M:%S")
time2=tupline1[1]-datetime.timedelta(0,3*freq/1.2)
STRtime2=time2.strftime("%Y-%m-%d %H:%M:%S")
## time.sleep(2*freq) ##the program needs to wait for 3*frequency/2 so that the next point is available in SQL data base for interpolation
cur.execute('SELECT * FROM bondtest_data WHERE DateTime BETWEEN %(date1)s AND %(date2)s ORDER BY DateTime',{'date1':STRtime2,'date2':STRtime1})
tupline2 = cur.fetchone() ##next point is fetched in order to find the slope of the line for temperature change
## print 'between2= ', tupline2[1]
deltay=float(float(tupline1[3])/10-float(tupline2[3])/10)
deltax = int(tupline1[1].strftime("%S"))-int(tupline2[1].strftime("%S"))
deltax = freq
## print "deltay= ", deltay
## print "deltax= ", deltax
slope = deltay/deltax
## print 'slope= ', slope
##in the following if statements depending on whether the temperature is increasing or decreasing the temperature for the desired point will be calculated
if (tupline2[3]<tupline1[3]):
tempsearchfor = float(tupline1[3])/10+delta*slope
## print '+delta*slope= ',delta*slope
elif (tupline2[3]>tupline1[3]):
tempsearchfor = float(tupline1[3])/10-delta*slope
## print '-delta*slope= ',delta*slope
else:
tempsearchfor = float(tupline1[3])/10
## print 'tempserachfor= ',tempsearchfor
#########################################################################
strng = [str(int(padsToVisualize[padCounter])),',',(d.strftime("%Y-%m-%d %H:%M:%S")),',',str(round(curTime,4)),',',str(inputVoltage),',']
str_one_line.extend(strng) ##str_one_line is the line that contains the values that will be written to the text file , the order is specified in the variables lists excel file
xyzCounter=Chan
EngUnits= array(range(50*1),dtype=float).reshape(50,1) ## constructing the array that will hold the 50 values for each set of signals and is later used for finding the average
average = array(range(3*1),dtype=float).reshape(3,1) ## holds the average of the t50 points for x,y,z
## straverage=array(range(3*1),dtype=str).reshape(3,1) ##this array will hold the strings for x,y,z signal to be written into txtfile
del straverage[:]
while(xyzCounter<3): ##the way the oven is set up it has x,y,z outputs from channel 0,1,2 accordingly
#n=cbDConfigPort(BoardNum,portNum,1)
#b=cbDOut(BoardNum,portNum,(63-padsToVisualize[padCounter])) #####based on Prof. Mayer's solution, the line sends the pad number that we are interested in to the DAQ to get the signals
a=0
time1=time.clock()
while (a<50): ## this while loop takes 50 measurements and writes the average of those points in to average array
#DataValue=cbAIn(BoardNum, xyzCounter, Gain)
#EngUnits[a,0]=float((cbToEngUnits(BoardNum,Gain,DataValue))/3/100*1000)
EngUnits[a,0] = random.uniform(0,0.5)
average[xyzCounter,0]=float(sum(EngUnits))/len(EngUnits)
a+=1
time2=time.clock()
timePerSample=(time2-time1)/50
print "time per sample= ",timePerSample
print "samples per second =", (1/timePerSample) ##measuring the frequency of the emasurements
tempstr=str(round((average[xyzCounter,0]),3)) ##in order to remove the two brackets temp refers to temporary
#tempstr=tempstr[1:-1]
straverage.append(tempstr)
xyzCounter+=1
#print average
temperaturearray=array(range(1*1),dtype=str).reshape(1,1)
temperaturearray=[str(tempsearchfor)]
three_sens_signals=array(range(1*5),dtype=str).reshape(1,5)
three_sens_signals=[str((straverage[0])),',',str((straverage[1])),',',str((straverage[2])),',']
str_one_line.extend(three_sens_signals)
str_one_line.extend(temperaturearray)
str_one_line.extend(',')
padCounter+=1
filename='log_simulation.txt'
f = open(filename,"a")
## writing to file section
print "padcounter=",padCounter," str_one_line=", str_one_line
for item in str_one_line:
f.write("%s" % item )
f.write("\n")
f.close()
curTime=time.clock()
答案 0 :(得分：1)
简而言之，在这段代码中有很多东西需要改进/重新编写（首先编辑所有import *语句并使用像你应该的命名空间）。话虽如此（代码显然大部分按原样工作），但问题出现的原因是存储在tupline或tupline2中的值因任何原因而为None。在代码中，使用sql语句
分配这些变量tupline = cur.fetchone()
tupline2 = cur.fetchone()
其中一个调用显然没有顺利运行（无论出于何种原因，数据或表已损坏），导致它返回“None”。也许有人正在删除或更换表格？您可以添加一些语义来检查此案例，报告并尝试继续。
的内容if tupline == None or tupline2 == None:
print "Why does tupline = None?"
continue
你应该知道sql .fetchone（）方法何时返回none。真的，你应该做一些更好的日志记录，但这可能会让你进入下一步调试。
答案 1 :(得分：0)
正如Paul Seeb所指出的，当代码到达tupline行时，会出现错误消息，因为tupline2或None为deltay=...。您的代码（成功）在到达tupline行之前访问deltay的元素。所以问题必须是tupline2。
我的猜测是数据库不包含tupline2查询的匹配记录;这肯定是要检查的东西。我还注意到，您在tupline2查询之前注释了一个延迟，提示此查询无法可靠地返回记录。我不知道你的程序逻辑，但你可以在tupline2查询之后用这样的行修复问题：
if tupline2 is None:
continue`
或者您可以重试tupline2查询，直到成功
while True:
cur.execute(
"""SELECT * FROM bondtest_data
WHERE DateTime BETWEEN %(date1)s AND %(date2)s
ORDER BY DateTime""",
{'date1':STRtime2,'date2':STRtime1}
)
tupline2 = cur.fetchone()
if tupline2 is None:
print "Failed to obtain a record for tupline2; trying again..."
time.sleep(<some duration>)
else:
break
我还注意到，每次进行循环时，您的代码都会创建一个新的数据库连接（db）并且从不显式关闭它。我建议将db = mdb.connect(...)命令移到主循环开头之上，或者在最后db.close()命令之后的某处添加fetchone()。您的代码很可能达到某种连接限制，但这可能会引发一个不同的异常。当db被重新分配并且旧连接超出范围时，您更有可能从某种自动关闭连接中受益。