Question

import threading
import time

def cold_temp():
    # Open the file that we viewed earlier so that python can see what is in it. Replace the serial number as before. 
    tfile = open("/sys/bus/w1/devices/28-021571bf69ff/w1_slave") 
    # Read all of the text in the file. 
    text = tfile.read() 
    # Close the file now that the text has been read. 
    tfile.close() 
    # Split the text with new lines (\n) and select the second line. 
    secondline = text.split("\n")[1] 
    # Split the line into words, referring to the spaces, and select the 10th word (counting from 0). 
    temperaturedata = secondline.split(" ")[9] 
    # The first two characters are "t=", so get rid of those and convert the temperature from a string to a number. 
    temperature = float(temperaturedata[2:]) 
    # Put the decimal point in the right place and display it. 
    temperature = temperature / 1000 
    return temperature

output = cold_temp()    
f = open('/var/www/html/coldtemp.html', 'w')
print >> f, output
f.close()
cold_temp()

我已尝试过上述和简单的

def cold_temp():
    while True:
        # Open the file that we viewed earlier so that python can see what is in it. Replace the serial number as before. 
        tfile = open("/sys/bus/w1/devices/28-021571bf69ff/w1_slave") 
        # Read all of the text in the file. 
        text = tfile.read() 
        # Close the file now that the text has been read. 
        tfile.close() 
        # Split the text with new lines (\n) and select the second line. 
        secondline = text.split("\n")[1] 
        # Split the line into words, referring to the spaces, and select the 10th word (counting from 0). 
        temperaturedata = secondline.split(" ")[9] 
        # The first two characters are "t=", so get rid of those and convert the temperature from a string to a number. 
        temperature = float(temperaturedata[2:]) 
        # Put the decimal point in the right place and display it. 
        temperature = temperature / 1000 
        return temperature

        output = cold_temp()    
        f = open('/var/www/html/coldtemp.html', 'w')
        print >> f, output
        f.close()
        time.sleep(1)

我想每秒运行一次脚本。以上两个都运行一次然后结束。

Answer 1

您可以使用sched模块安排重复运行的内容，无论是每两小时还是每一秒。

如果您的功能运行时间超过一秒（不太可能只检查温度），那么您将有延迟。

你也会看到一些＆＃34;漂移＆＃34;在时间上由于你的功能运行所花费的时间，因为它反复安排。所有微小的＆＃34;位＆＃34;你的功能运行所需的时间最终会加起来。

e.g。 -

import sched, time

s = sched.scheduler(time.time, time.sleep)
def some_function():

    print time.time()
    s.enter(1, 0, some_function)

s.enter(1, 0, some_function)
s.run()

Answer 2

您的while循环位置错误。我冒昧地改变你的代码来使用with子句，这是打开文件的更标准的方法，但如果你有一个非常古老的python，它将会中断。

import threading
import time

def cold_temp():
    # Open the file that we viewed earlier so that python can see what is in it. Replace the serial number as before. 
    with open("/sys/bus/w1/devices/28-021571bf69ff/w1_slave") as tfile:
        # skip first line, keep second line
        next(tfile)
        secondline = next(tfile)
    # Split the line into words, referring to the spaces, and select the 10th word (counting from 0). 
    temperaturedata = secondline.split(" ")[9] 
    # The first two characters are "t=", so get rid of those and convert the temperature from a string to a number. 
    temperature = float(temperaturedata[2:]) 
    # Put the decimal point in the right place and display it. 
    temperature = temperature / 1000 
    return temperature

while True:
    output = cold_temp()    
    with open('/var/www/html/coldtemp.html', 'w') as f:
        print >> f, output
    time.sleep(1)

Answer 3

第一个运行一次，因为你没有给它任何重复运行的方法。第二个命中return，它甚至在有机会输出任何东西之前退出函数（从而退出循环）。移除return，然后使用temperature获取output的值。

Python没有每秒运行

3 个答案: