writing on file not until the end

[John Machin]

On May 25, 6:30 pm, Alessandro <zasaconsult... at gmail.com> wrote:
> On May 25, 8:38 am, Peter Otten <__pete... at web.de> wrote:
>
>
>
> > Alexzive wrote:
> > > I am a newby with python. I wrote the following code to extract a text
> > > from a file and write it to another file:
>
> > > linestring = open(path, 'r').read() #read all the inp file in
> > > linestring
>
> > > i=linestring.index("*NODE")
> > > i=linestring.index("E",i)
> > > e=linestring.index("*",i+10)
> > > textN = linestring[i+2:e-1] # crop the ELement+nodes list
> > > Nfile = open("N.txt", "w")
> > > Nfile.write(textN)
>
> > > unfortunately when I check N.txt some lines are missing (it only crop
> > > until "57, 0.231749688431, 0.0405121944142" but I espect the final
> > > line to be "242, 0.2979675, 0.224605896461". I check textN and it has
> > > all the lines until "242..")
>
> > > when I try Nfile.write(textN) again it writes some more lines but
> > > still not all!
> > > what is wrong whit this?
>
> > Do you check the contents of the resulting file by feeding it to another
> > program?
>
> > > 53, 0.170973146505, 0.0466686190136
> > > 57, 0.231749688431, 0.0405121944142
> > > t60, 0.250420691759, 0.0399644155193
> > > 58, 0.234883810317, 0.0488399925217
> > > 61, 0.2666025, 0.03541845
>
> > There's a "t" at the start of the line after the last line you claim to see,
> > so maybe your input file is corrupt and your reader stumbles over that line.
>
> > Peter
>
> Thank you all for replying.
>
> - yes, I oversaw the "t" at "60, 0.250420691759, 0.0399644155193". I
> then removed it for the following tests
> - changing from "e-1" to "e" apparently solved the problem, BUT I then
> realized it was just because a second access to the file (still open)
> seems to be the real solution --> after Nfile.close() e retrying with
> "e" instead of "e-1" the problem is still there.
> - I also tryied to inizialize e and i to zero --> nothing changes
> - until now, the only solution which works is to repeat the code while
> the file is still open, which means a quite redundant code:
>
> linestring = open(path, 'r').read()
> i=linestring.index("*NODE")
> i=linestring.index("E",i)
> e=linestring.index("*",i+10)
> textN = linestring[i+2:e-1] # crop the ELement+nodes list
> Nfile = open("N.txt", "w")
> Nfile.write(textN)

Insert here:
Nfile.close()

Remove the redundant second pass.

> linestring = open(path, 'r').read()
> i=linestring.index("*NODE")
> i=linestring.index("E",i)
> e=linestring.index("*",i+10)
> textN = linestring[i+2:e-1] # crop the ELement+nodes list
> Nfile = open("N.txt", "w")
> Nfile.write(textN)