python - 属性错误 : 'NoneType' object has no attribute 'group'

Question

请帮忙，因为我正在尝试使用 raspberry pi pir 传感器将 pir 传感器收集的数据(即 1 或 0)传输到网络服务我得到了这个错误

Traceback (most recent call last):
  File "pir_5.py", line 54, in <module>
    moveHold = float(matches.group(1))
AttributeError: 'NoneType' object has no attribute 'group'

这是我的代码

while True :

    # Read PIR state
    Current_State = GPIO.input(GPIO_PIR)

    if Current_State==1 and Previous_State==0:
      # PIR is triggered
      output =  subprocess.check_output(["echo", "18"]);
      print "  Motion detected!"
      # Tell the Pi to run our speech script and speak the words
      # motion dtected! - anything after the .sh will be read out.
      matches = re.search("Current_State==1 and Previous_State==0", output)
      moveHold = float(matches.group(1))
      resultm = client.service.retrieveMove(moveHold)

      cmd_string = './speech.sh motion detected!'
      # now run the command on the Pi.
      os.system(cmd_string)
      # Record previous state
      Previous_State=1
    elif Current_State==0 and Previous_State==1:
      # PIR has returned to ready state
      print "  Ready"
      Previous_State=0

    # Wait for 10 milliseconds
    time.sleep(0.01)

Answer 1

显然 output 不包含预期的字符串。 (当它是通过调用 echo 18 生成时应该如何？)因此，

  matches = re.search("Current_State==1 and Previous_State==0", output)

返回None，它没有.group() for

  moveHold = float(matches.group(1))

这样你就得到了上述异常。

你应该把它改成

    matches = re.search("Current_State==1 and Previous_State==0", output)
    if matches:
        moveHold = float(matches.group(1))
        resultm = client.service.retrieveMove(moveHold)
        ...
    else:
        # code for if it didn't match