如何在python脚本中传递变量

Question

我有一个 python 脚本，它使用两个函数，但其​​中一个函数无法正常工作。 main() 调用第一个函数Define_and_Collect_1_WireData():这按预期工作。 但是，我无法将函数Define_and_Collect_1_WireData():的字符串变量data_stream_logfile传递给函数log_file() 。

我没有使用return因为我不确定这会使变量保持局部而不是全局。

我尝试了本网站上提供的许多组合/变体：我无法理解的任何组合/变体都有效。

我怎样才能做到这一点？

#!/usr/bin/env python

import time

# Create a useful time stamp for logging to the log file 
timestamp = time.strftime("%d/%m/%Y %H:%M:%S")


def Define_and_Collect_1_WireData():
    tfile = open("/sys/bus/w1/devices/28-0000052c29e1/w1_slave")
    text = tfile.read()
    tfile.close()
    temperature_data = text.split()[-1]
    temperature = float(temperature_data[2:])
    temperature1 = round(temperature / 1000,1)

    #for the purposes of testing. Temperature1 will be pulled from the Dallas 1-wire bus 
    temperature1=13.1

    # Create data_stream_logfile string
    data_stream_logfile = str(temperature1) + "," + str(timestamp)

    # Print output to a terminal
    print "Raw temperature data as written to log file:"
    print data_stream_logfile
    print " "

def log_file():
    # Open the text log datafile
    datafile_temperature_log = open("log_cron_temperature_data.log", "a", 1)
    datafile_temperature_log.write(data_stream_logfile + "\n")
    datafile_temperature_log.close()



def main():

    Define_and_Collect_1_WireData()

    log_file()

main()

Answer 1

您应该从第一个函数返回它并将其传递给第二个函数：

def Define_and_Collect_1_WireData():
    # stuff...

    # Create data_stream_logfile string
    data_stream_logfile = str(temperature1) + "," + str(timestamp)

    # More stuff
    return data_stream_logfile

def log_file(data_stream_logfile):
    # Open the text log datafile
    datafile_temperature_log = open("log_cron_temperature_data.log", "a", 1)
    datafile_temperature_log.write(data_stream_logfile + "\n")
    datafile_temperature_log.close()



def main():

    data_stream_logfile = Define_and_Collect_1_WireData()

    log_file(data_stream_logfile)

main()

所以，永远，永远，永远尽量不要使用全局变量！！！！

Answer 2

您需要在Define_and_Collect_1_WireData函数中返回data_stream_logfile的值，并将其传递给log_file() ：

def Define_and_Collect_1_WireData():
  ...
  data_stream_logfile = str(temperature1) + "," + str(timestamp)
  return data_stream_logfile

def log_file(data_stream):
  ...

def main():
    data_stream = Define_and_Collect_1_WireData()
    log_file(data_stream)

Answer 3

#!/usr/bin/env python

import time

# Create a useful time stamp for logging to the log file 
timestamp = time.strftime("%d/%m/%Y %H:%M:%S")


def Define_and_Collect_1_WireData():
    tfile = open("/sys/bus/w1/devices/28-0000052c29e1/w1_slave")
    text = tfile.read()
    tfile.close()
    temperature_data = text.split()[-1]
    temperature = float(temperature_data[2:])
    temperature1 = round(temperature / 1000,1)

    #for the purposes of testing. Temperature1 will be pulled from the Dallas 1-wire bus 
    temperature1=13.1

    # Create data_stream_logfile string
    data_stream_logfile = str(temperature1) + "," + str(timestamp)

    # Print output to a terminal
    print "Raw temperature data as written to log file:"
    print data_stream_logfile
    print " "

    return data_stream_logfile

def log_file(data_stream_logfile):
    # Open the text log datafile
    datafile_temperature_log = open("log_cron_temperature_data.log", "a", 1)
    datafile_temperature_log.write(data_stream_logfile + "\n")
    datafile_temperature_log.close()



def main():

    log_file (Define_and_Collect_1_WireData())

main()

Answer 4

您可以写入本地data_stream_logfile并将其返回给调用者。 然后调用log_file(data_stream_logfile)

或者您可以在第一个函数中使用参数data_stream_logfile调用log_file() 。

或者您可以将其设置为全局变量以从您的两个函数中访问。 请记住将global data_stream_logfile放入您的每个函数中。

最后一种是不鼓励的，因为它容易出错。

Answer 5

这是范围的问题。 当您调用DaC1WD （因为这是一个非常长的函数名），它会在其中为日志创建一个变量。 当函数完成时，它里面的所有东西都丢失了。 您需要做的是return日志文件，然后将日志文件作为参数调用记录器。

Answer 6

您应该在函数中使用返回值和参数。 例如，您可以按如下方式重写脚本：

#!/usr/bin/env python

import time

# Create a useful time stamp for logging to the log file 
timestamp = time.strftime("%d/%m/%Y %H:%M:%S")


def define_and_collect_1_wire_data():
    tfile = open("/sys/bus/w1/devices/28-0000052c29e1/w1_slave")
    text = tfile.read()
    tfile.close()
    temperature_data = text.split()[-1]
    temperature = float(temperature_data[2:])
    temperature1 = round(temperature / 1000,1)

    #for the purposes of testing. Temperature1 will be pulled from the Dallas 1-wire bus 
    temperature1=13.1

    # Create data_stream_logfile string
    data_stream_logfile = str(temperature1) + "," + str(timestamp)

    # Print output to a terminal
    print "Raw temperature data as written to log file:"
    print data_stream_logfile
    print " "
    return data_stream_logfile

def log(message):
    # Open the text log datafile
    datafile_temperature_log = open("log_cron_temperature_data.log", "a", 1)
    datafile_temperature_log.write(message + "\n")
    datafile_temperature_log.close()



def main():

    log_file(define_and_collect_1_wire_data())

main()

Answer 7

您必须将变量设为全局变量，因为它当前是该特定函数的本地变量。

global data_stream_logfile
data_stream_logfile = str(temperature1) + "," + str(timestamp)

这将使您可以在程序中的任何其他地方使用它

希望我能帮上忙：3