[Tutor] Using 'with open' statementfor reading a file two lines at a time

[Mark Lawrence]

On 27/11/2020 01:32, Ken Green wrote:
> On 11/26/20 8:00 PM, Alan Gauld via Tutor wrote:
>> On 27/11/2020 00:37, Ken Green wrote:
>>
>>> I am using 'with open' statement to read a file two lines at a time and
>>> then combining them together to print the results into another file.
>> Please don't just describe your code and think we can guess
>> what you've done.
>>
>> Post the actual code and any actual error messages in full.
>>
>> There must be at least half a dozen ways to do what you describe.
>> We can't fix what we can't see.
>>
>>> How can I continue reading the third and fourth lines and so forth on
>>> until the end of the file?
>> You need to use a loop, either a 'while' or 'for'
>> But without seeing what you've done so far I can't say more than that.
>>
>>> (2020-11-5) as an interface. I used to use Geany but discovered the
>>> latest version doesn't work in Ubuntu 20.04 and it only applicable for
>>> Windows and Apple and there is no Linux version according to its 
>>> website.
>> I'm pretty sure there is a Linux version, in fact I just checked
>> and v1.37 has just been released on Linux as well as Windoze and
>> MacOS.
>> v1.36 is available in the software tool for my Linux Mint 20 which
>> is based on Ubuntu 20 so you should definitely be able to get
>> it working.
>>
>> But if not there are a zillion other code editors out there that
>> will do just fine!
> I humbly apologized Alan. Below is the code:
> 
> # Daily Three Pick Three 99 Combine Test py
> # 11/26/2020
> import sys
> filename1 = "Pick_Three_Drawings_File.txt"
> filename2 = "Pick_Three_Drawings_File_Combine.txt"
> file1 = open(filename1, "r")
> file2 = open(filename2, "w")
> with open(filename1) as file1:
>      line1 = file1.readline().strip()
>      line2 = file1.readline().strip()

There's no loop so you'll only ever read two lines from the file.  See 
this 
https://stackoverflow.com/questions/1657299/how-do-i-read-two-lines-from-a-file-at-a-time-using-python 
for how to read two lines at a time.

>      line3 = (line1 + line2)
>      line4 = (line3[ 0: 4] + line3[ 4: 6] + line3[ 6: 8] + line3[ 8: 9] 
> + line3[ 9:12] + line3[20:21] + line3[21:24])
>      file2.write(line4)
> file1.close()
> file2.close()
> 

You don't need the calls to 'close', the 'with open' does that 
automatically.

-- 
My fellow Pythonistas, ask not what our language can do for you, ask
what you can do for our language.

Mark Lawrence