Question

下面是我在python中编写的一些代码，它安排在crontab上，每15分钟运行一次。它应该检查我的覆盆子pi上CPU的温度，并发短信给我，询问如果温度高于45摄氏度该怎么办。我知道我收到了正确的温度值，因为它以数字的形式打印到屏幕上。但是，我似乎每15分钟收到一条短信，说明它的温度甚至低于45度。我知道错误必须在我的条件某处，但我是python语法的新手，无法弄明白。我曾尝试使用＆gt;比较45和45.0。和＆gt; =。

import os
import smtplib
import sys

# Return CPU temperature as a character string                                      
def getCPUtemperature():
    res = os.popen('vcgencmd measure_temp').readline()
    return(res.replace("temp=","").replace("'C\n",""))

# CPU informatiom
CPU_temp = getCPUtemperature()

if CPU_temp > 45.0:
    fromaddr = 'xxxxxxxxxx@gmail.com'
    toaddrs  = 'xxxxxxxxxx@vtext.com'
    msg = 'My current CPU temperature is %s degrees. Should I shutdown?' % (CPU_temp)
    # Credentials (if needed)  
    username = 'xxxxxxxxxx'
    password = 'xxxxxxxxxx'
    # The actual mail send  
    server = smtplib.SMTP('smtp.gmail.com:587')
    server.starttls()
    server.login(username,password)
    server.sendmail(fromaddr, toaddrs, msg)
    server.quit()
    sys.exit()
else:
    sys.exit()

Answer 1

您无法将字符串（由getCPUtemperature返回）与float 45.0进行比较，请尝试将字符串转换为float：

import os
import smtplib
import sys

# Return CPU temperature as a character string                                      
def getCPUtemperature():
    res = os.popen('vcgencmd measure_temp').readline()
    return(res.replace("temp=","").replace("'C\n",""))

# CPU informatiom
CPU_temp = getCPUtemperature()

if float(CPU_temp) > 45.0:
    fromaddr = 'xxxxxxxxxx@gmail.com'
    toaddrs  = 'xxxxxxxxxx@vtext.com'
    msg = 'My current CPU temperature is %s degrees. Should I shutdown?' % (CPU_temp)
    # Credentials (if needed)  
    username = 'xxxxxxxxxx'
    password = 'xxxxxxxxxx'
    # The actual mail send  
    server = smtplib.SMTP('smtp.gmail.com:587')
    server.starttls()
    server.login(username,password)
    server.sendmail(fromaddr, toaddrs, msg)
    server.quit()
    sys.exit()
else:
    sys.exit()

Answer 2

取决于getCPUtemperature()返回的内容。如果该方法返回一个字符串，例如＆＃34; 15＆＃34;，则条件为真。

>>> "15" > 45.0
>>> True

>>> "64" > 45.0
>>> True

在if条件之前将getCPUtemperature()的返回值转换为float。

Answer 3

CPU_temp需要显式转换为float，因为你要返回一个字符串。你可以像CPU_temp = float(CPU_temp)一样转换它，或者只是在比较中进行转换。以下是对正在发生的事情的痕迹解释：

>>> CPU_temp = "53.1"
>>> if CPU_temp > 45.0:
    print("True")
TypeError: unorderable types: str() > float()

>>> if float(CPU_temp) > 45.0:
    print("True")
True

python代码的问题

3 个答案: