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Jan 31st, 2007
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how to remove a number of lines from a text file ?

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Hi,

I have jest started learning Python.

I would like to get some help on writing a script that would delete a set number of lines from a text file which looks like this :

1846440556
1846440521
1846440491
1846440505
1846441137
1846441102
1846441080
1846441331
1846441323
1846441315
...
...

Thanks in advance

Cornholio
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Cornholio is offline Offline
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Jan 31st, 2007
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Re: how to remove a number of lines from a text file ?

Here is an example how to do this. I had to create your kind of data file first to use it properly ...
python Syntax (Toggle Plain Text)
  1. data_str = """\
  2. 1846440556
  3. 1846440521
  4. 1846440491
  5. 1846440505
  6. 1846441137
  7. 1846441102
  8. 1846441080
  9. 1846441331
  10. 1846441323
  11. 1846441315"""
  12.  
  13. # let's create your data file from the string
  14. fout = open("MyData1.txt", "w")
  15. fout.write(data_str)
  16. fout.close()
  17.  
  18. # read the data file in as a list
  19. fin = open( 'MyData1.txt', "r" )
  20. data_list = fin.readlines()
  21. fin.close()
  22. # test it ...
  23. print data_list
  24.  
  25. print '-'*60
  26.  
  27. # remove list items from index 3 to 5 (inclusive)
  28. del data_list[3:5+1]
  29. # test it ...
  30. print data_list
  31.  
  32. # write the changed data (list) to a file
  33. fout = open("MyData2.txt", "w")
  34. fout.writelines(data_list)
  35. fout.close()
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vegaseat is offline Offline
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Re: how to remove a number of lines from a text file ?

Thanks fot your help.
I have now modified the script to read the lines from a file. The Python interpreter gives me an error message. What is wrong with the modified code ?
data1 = open('list.txt', "r")
data_str = data1.readlines()
data1.close()
# create your data file from the string
# try 'wb'?
fout = open("MyData1.txt", "w")
fout.write(data_str)
fout.close()

# read the data file in as a list
fin = open( 'MyData1.txt', "r" )
data_list = fin.readlines()
fin.close()
# test it ...
print data_list

print '-'*60

# remove list items from index 3 to 5 (inclusive)
del data_list[3:200+1]
# test it ...
print data_list

# write the changed data (list) to a file
fout = open("MyData2.txt", "w")
fout.writelines(data_list)
fout.close()
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Re: how to remove a number of lines from a text file ?

What is your error message?
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bumsfeld is offline Offline
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Re: how to remove a number of lines from a text file ?

the error message is:

File "C:\!cutout\cutOut.py", line 6, in <module>
fout.write(data_str)
TypeError: argument 1 must be string or read-only character buffer, not list
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Feb 6th, 2007
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Re: how to remove a number of lines from a text file ?

Looks like you really butchered vegseat's code. Let me rewrite it a little:
Python Syntax (Toggle Plain Text)
  1. """ assume part of your list1.txt data file looks like this:
  2. 1846440556
  3. 1846440521
  4. 1846440491
  5. 1846440505
  6. 1846441137
  7. 1846441102
  8. 1846441080
  9. 1846441331
  10. 1846441323
  11. 1846441315
  12. """
  13.  
  14. # read the data file in as a list
  15. fin = open( 'list1.txt', "r" )
  16. data_list = fin.readlines()
  17. fin.close()
  18. # test first 5 list items ...
  19. print data_list[:5]
  20.  
  21. print '-'*60
  22.  
  23. # remove list items from index 3 to 5 (inclusive)
  24. del data_list[3:5+1]
  25. # test first 5 list items ...
  26. print data_list[:5]
  27.  
  28. # write the changed data (list) to a file
  29. fout = open("list2.txt", "w")
  30. fout.writelines(data_list)
  31. fout.close()
Last edited by vegaseat; Jan 7th, 2010 at 9:18 am. Reason: code tags
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bumsfeld is offline Offline
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Feb 7th, 2007
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Re: how to remove a number of lines from a text file ?

Big Thanks to all of you for help.

bumsfeld, your code does exactly what I wanted.

Cornholio - an absolute beginner
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Jan 7th, 2010
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Re: how to remove a number of lines from a text file ?
When i try to use this code i still have the data in the orginial filem how do i remove them from the first file?
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Re: how to remove a number of lines from a text file ?
Click to Expand / Collapse  Quote originally posted by Godflesh ...
When i try to use this code i still have the data in the orginial filem how do i remove them from the first file?
Replace
fout = open("list2.txt", "w")
with
fout = open("list1.txt", "w")
to overwrite the original file.
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Re: how to remove a number of lines from a text file ?
thanks, offcourse
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