How to write last 50 lines from one file to another Python

Question

I am creating an email response to an overnight build, I want to get the last 50 lines from the results file and place it into a summary file. The code that I have done is below, can anyone help?

def email_success():

    fp = open(results_file, 'r')

    sum_file = (fp.readlines()[-50:])
    fp.close()

    myfile = open(result_summary,'w')

    myfile.write(sum_file)
    myfile.close()

I have got the error message below when trying this code:

Traceback (most recent call last):
  File "email_success.py", line 76, in <module>
    if __name__ == '__main__': myObject = email_success()
  File "email_success.py", line 45, in email_success
    myfile = open(result_summary,'w')
TypeError: coercing to Unicode: need string or buffer, tuple found

Thanks

The results summary is a variable that stores an address.

result_summary = (t, 'results_summary.txt')

Sorry made a stupid mistake, I forgot to add os.path.join

result_summary = os.path.join(t, 'results_summary.txt')

Thanks for the help

@alok It is a directory address, I forgot to add the os.join to make it one string. This is what was causing the error

Answer 1

TypeError: coercing to Unicode: need string or buffer, tuple found

Error says its expect string or buffer but you are passing tuple , so just join it with "" to make it to string

So, Try

sum_file = "".join(fp.readlines()[-50:])

UPDATE : because OP updated the question

if result_summary = (t, 'results_summary.txt')

Try

myfile = open(result_summary[1],'w')

Answer 2

它是open（）引发异常，但是...您如何定义result_summary？

Answer 3

result_summary is a tuple, it needs to be either a str or buffer. Your explanation has nothing to do with the error you posted.

Answer 4

result_summary = (t, 'results_summary.txt')

and

 myfile = open(result_summary,'w')

means

 myfile = open((t, 'results_summary.txt'),'w')

which obviously won't work, try:

 myfile = open(result_summary[1],'w')

instead

Answer 5

fp.readlines() method returns a list of lines. Therefore you can't apply [-50:] operator.