Insert character at a fixed position of lines

[Francesco Pietra]

Sorry to come again for the same problem. On commanding:

$ python script.py 2>&1 | tee fileout.pdb

nothing occurred (fileout.pdb was zero byte). The script reads:

f = open("xxx.pdb", "w")
f.write('line = line[:22] + "A" + line[23:]')
f.close()

File xxx.pdb is opened by the command: when I forgot the single quote
' after [23:] the error answer was:
SynthaxError: EOL while scanning single-quoted string.

Thanks
francesco

On Sat, Jul 26, 2008 at 1:10 PM, Lie <Lie.1296 at gmail.com> wrote:
> On Jul 26, 5:42 pm, "Francesco Pietra" <chiendar... at gmail.com> wrote:
>> I am still at the stone age, using scripts (e.g., to insert a string
>> after a string) of the type
>>
>> f = open("xxx.pdb", "r")
>> for line in f:
>>    print line
>>    if "H16Z POPC" in line:
>>        print "TER"
>> f.close()
>>
>> That is, I have to learn about modules. In your scripts I am lost
>> about the filename for the pdb file to modify,
>
> In Python, stdin and stdout (as provided by the sys module) is a file-
> like object, i.e. it have similar behavior as regular files you opened
> with open(). stdin is a read-only file, while stdout is a write-only
> file. You already know how to make read-only file, f = open("xxx.pdb",
> "r"), to make it writable, you've got to use 'w' as the mode: f =
> open("xxx.pdb", "w")
>
> After that you can do this:
> f.write('some string')
>
>
>> francesco
>>
>>
>>
>> On Sat, Jul 26, 2008 at 11:35 AM, Lie <Lie.1... at gmail.com> wrote:
>> > On Jul 26, 2:41 pm, "Francesco Pietra" <chiendar... at gmail.com> wrote:
>> >> How to insert letter "A" on each line (of a very long list of lines)
>> >> at position 22, i.e., one space after "LEU", leaving all other
>> >> characters at the same position as in the original example:
>>
>> >> ATOM      1  N   LEU     1     146.615  40.494 103.776  1.00 73.04       1SG   2
>>
>> >> In all lines"ATOM" is constant as to both position and string, while
>> >> "LEU" is constant as to position only, i.e., "LEU" may be replaced by
>> >> three different uppercase letters. Therefore, the most direct
>> >> indication would be position 22.
>>
>> >> Should the script introduce blank lines, no problem. That I know how
>> >> to correct with a subsequent script.
>>
>> >> Thanks
>> >> chiendarret
>>
>> > If you want to leave the rest of the strings as-is (i.e. the letter A
>> > overwrites whatever on position 22), Peter's code need to be modified
>> > a little:
>> > line = line[:22] + " " + line[23:]
>> > --
>> >http://mail.python.org/mailman/listinfo/python-list
>>
>> --
>> Dr Francesco Pietra
>> Professor of Chemistry
>> Accademia Lucchese di Scienze, Lettere e Arti, founded in 1594
>> Palazzo Ducale
>> 55100 Lucca (Italy)
>> e-mail chiendar... at gmail.com
>
> --
> http://mail.python.org/mailman/listinfo/python-list
>