Python: how can a delay the repeat of my print command?

Question

My objective is to program a print out a reading, but I want to delay the reprint so that its not spamming me with the reading constantly.

try:
  cpuFile=open("/sys/class/thermal/thermal_zone0/temp","","r")
  cpuTemp=float(cpuTempFile.read())/1000
  cpuTempFile.close()
  if(abs(cpuTemp-cpuTempOld > hyst)):
    print("Pin {0} is ON".format(FAN_PIN))
    sleep(30)   # I've tried the sleep command like this
     # but it didnt do the trick

This obviously isn't created by me and I also didn't provide the entire code, this is just want I believe you will need to have an understanding of what I'm trying to do.

Answer 1

Question

How to sleep for some time and read a closed file and print it?

Answer

I guess what you wish to do is the following.

1. You already have another program or function that reads the CPU temperature, probably from the CPU FAN pin output, perhaps once every second, and write or append the temperature readings in a text file.

2. You don't want to read and print the temperature readings too often.

3. So you only print the readings one by one, between sleeping for 5 seconds, say.

Now let me suggest to eat the big elephant by two bites:

Bite 1 - How to open/write/read/print a text file

You might like to read my program doing that in the following post. There is a minimal, complete, and verifiable program with sample output. You just plug and play. Check the results output to make sure everything goes smoothly.

How to open/write/read/print a text file? - tlfong01

Bite 2 - How to open an old file, read something, and print it with delay.

Now I have changed the above program a little bit and add sleeps between printing something. An sample output is listed below:

  Now opening text file 

  Now writing a line to text file 

  Now closing text file 

  Now sleeping 4 seconds, ... 

  Now printing text file

Below is a complete listing of the minimal, complete, verifiable program. Again you just plug and play. I am using Chinese Windows, so you might see funny characters in the print output. In that case, you might try my PenZu backup file below.

tlfong01's PenZu delay print text file program listing

1:07PM SAT. 4/20/2019


# *** write_test_file_test06 tlfong01 2019apr20hkt1257 ***

import datetime
from time import sleep

# *** Text file functions ***

# *** Open/Close Text File ***

def openTextFileToWrite(textFileName):
    textFileObject = open(textFileName, 'w')
    return textFileObject

def openTextFileToRead(textFileName):
    textFileObject = open(textFileName, 'r')
    return textFileObject

def closeTextFile(textFileObject):
    textFileObject.close()
    return

# *** Write/Read/Print Text File ***

def writeTextString(textFileObject, writeString):
    textFileObject.write(writeString)
    return

def printTextFile(textFileName):
    textFileObject = open(textFileName, 'r')    
    for line in textFileObject:
        print(line) 
    textFileObject.close()    
    return

# *** Test Functions ***

def writeTimeNowString(textFileObject):
    textFileObject.write('\r\n' + str(datetime.datetime.now()))
    return

def testWriteReadPrintTextFile(textFileName):   
    textFileObject = openTextFileToWrite(textFileName)
    writeTimeNowString(textFileObject)
    closeTextFile(textFileObject)   
    printTextFile(textFileName)
    return

def testWriteReadPrintSleepTextFile(textFileName):
    print('')
    print('  Now opening text file                   ', textFileName, '\r\n')
    textFileObject = openTextFileToWrite(textFileName)
    print('  Now writing a dateTime line to text file', textFileName, '\r\n')    
    writeTimeNowString(textFileObject)
    writeTimeNowString(textFileObject)
    print('  Now closing text file                   ', textFileName, '\r\n')      
    closeTextFile(textFileObject)
    print('  Now sleeping 4 seconds, ...', '\r\n')
    sleep(4)
    print('  Now printing text file                  ', textFileName, '\r\n')     
    printTextFile(textFileName)
    return

# *** Main ***

print('Begin testWriteReadPrintTextFile, ...')
#testWriteReadPrintTextFile('testFile01.txt')
testWriteReadPrintSleepTextFile('tom.txt')
print('\r\nEnd    testWriteReadPrintTextFile.')

# *** Sample Output ***

'''
>>> 
 RESTART: /home/pi/Python Programs/Python_Programs/test1197/test_text_file_05_2019apr2001.py 
Begin testWriteReadPrintTextFile, ...

  Now opening text file                    tom.txt 

  Now writing a dateTime line to text file tom.txt 

  Now closing text file                    tom.txt 

  Now sleeping 4 seconds, ... 

  Now printing text file                   tom.txt 

2019-04-20 12:59:18.491911

2019-04-20 12:59:18.492096

End    testWriteReadPrintTextFile.   testWriteReadPrintTextFile.
>>> 
'''

# *** End ***



1:07PM SAT. 4/20/2019

Update 2019apr22hkt1112

[Introduction to Computer Science and Programming in Python {2.7?] - MIT OCW]3

Introduction to Computer Science and Programming Using Python [3.5?]

Answer 2

In Python you can create a delay using time.sleep(), for example to pause for 10 seconds:

import time
....
time.sleep(10)

An alternative, exactly equivalent, way of writing this would be:

from time import sleep
....
sleep(10)