Python3 -更新内部循环中的“power”变量会修改外部循环的聚合变量

Question

我通读了一个目录中的所有文件(csv文件)-我忽略了每个文件的前7行“header”，然后找到了从第8行到第151行的时间和功率值。我读到的每一行都是示例行6-9和46-48的形式

Time;Power
HH:mm;kW
00:10;0.000
00:20;0.000
<snip>
06:20;0.012
06:30;0.042
06:40;0.060

我的代码成功地忽略了所有午夜后的零读数，并正确地识别了06:20的第一个非零功率读数。它使用时间(小时和分钟)来调整一个变量，该变量包含当天的时间戳，并将现在的小时/分钟包含的时间戳和功率存储在一个复杂的变量timePower[(timestamp),(power)]中。然后，它将变量timePower[(),()]附加到变量dayPower[]中，并再次从文件的下一行开始。

由于我不能计算出的原因，下一行解析正常，直到我用新的时间戳更新timePower[0]，用新的幂更新timePower[1] -更新这些变量似乎也更新了dayPower[]变量(dayPower[0])中的现有条目，现在，就在我要追加一个新条目之前，旧的条目看起来与新的条目相同。新行成功追加。重复这种错误行为，直到我读取完所有非零值，并且dayPower[]中的所有行看起来都与最终条目相同。相关函数如下所示：

def parse_power_values(path, filename, theDate):
  timePower = [(),()] #a list that will be assigned two items; the timestamp and the power for that timeslot
  dayPower = [] # A list that will have all the timePowers for the day appended
  currentFile = open(path + filename,'r')
  for i, line in enumerate(currentFile):
    if i <= 7:
      doingSomething = True
      #print 'header' + str(i) + '/ ' + line.rstrip()
    elif ((i > 7) and (i <= 151)):
      lineParts = line.split(';')
      theTime = lineParts[0].split(':')
      theHour = theTime[0]
      theMin = theTime[1]
      timestamp = theDate.replace(hour=int(theHour),minute=int(theMin)) #theDate is a timestamp obj with the current date but hour & minute at 00:00 to start with.
      power = lineParts[1].rstrip()
      if power == '-.---':
        power = 0.000
      if (float(power) > 0):
        #append_to_database(con, timestamp,power)
        timePower[0] = timestamp
        timePower[1] = power
        dayPower.append(timePower)
    elif i > 151:
     return dayPower
     #break
  currentFile.close()

Answer 1

@jasonharper是对的，我修改后的函数现在看起来像这样：

def parse_power_values(path, filename, theDate):
  # timePower = [(),()] #a list that will be assigned two items; the timestamp and the power for that timeslot
  dayPower = [] # A list that will have all the timePowers for the day appended
  currentFile = open(path + filename,'r')
  for i, line in enumerate(currentFile):
    if i <= 7:
      doingSomething = True
      #print 'header' + str(i) + '/ ' + line.rstrip()
    elif ((i > 7) and (i <= 151)):
      lineParts = line.split(';')
      theTime = lineParts[0].split(':')
      theHour = theTime[0]
      theMin = theTime[1]
      timestamp = theDate.replace(hour=int(theHour),minute=int(theMin))
      power = lineParts[1].rstrip()
      if power == '-.---':
        power = 0.000
      if (float(power) > 0):
        dayPower.append([timestamp,power])
    elif i > 151:
     return dayPower
     #break
  currentFile.close()