[Tutor] A Multiple Concatenation Problem

[Mats Wichmann]

On 9/18/20 7:34 AM, Stephen P. Molnar wrote:
> 
> 
> On 09/17/2020 02:00 PM, Alan Gauld via Tutor wrote:
>> On 17/09/2020 18:54, Mats Wichmann wrote:
>>
>>>>>> for suf in range(1, 11):
>>> ...     filename = f"<ligand>{suf}.log"
>>> ...     print(filename)
>>> ...
>>> <ligand>1.log
>>> <ligand>2.log
>>> <ligand>3.log
>>> <ligand>4.log
>>> <ligand>5.log
>>> <ligand>6.log
>>> <ligand>7.log
>>> <ligand>8.log
>>> <ligand>9.log
>>> <ligand>10.log
>>
>> In case that's not clear, Mats is using the new
>> format-string notation.
>> You can use the old style format strings similarly:
>>
>> fmt = "<ligand>.%d.log"
>> for suf in range(1,11):
>>     print(fmt % suf)
>>
>> Or append to a list or...
>> rather than print...
>>
> I read the data in with:
> 
> filename = 'Ligand.list'
> file = open(filename,mode='r')
> text = file.read()
> file.close()
> 
> where Ligand.list, for testing, as at this point I have 31 ligands to
> process, contains
> 
> 2-Pholoeckol
> 7-Pholoeckol
> 
> If I use either:
> 
> fmt = "<ligand>.%d.log"
> for suf in range(1,11):
>    print(fmt % suf)
> 
> or
> for suf in range(1, 11):
>    filename = f"<ligand>{suf}.log"
>    print(filename)
> 
> I get the same result: 2-Pholoeckol.1.log to 2-Pholoeckol.10.log
>                        7-Pholoeckol.1.log to 7-Pholoeckol.10.log
>                       
> Obviously I'm missing something very fundamental, and I'm quite
> embarrassed by that, but how di I get the ligand name rather than
> <ligand>... ?

You didn't say so, though I kind of suspected <ligand> wasn't literal,
but a placeholder.  We just took it literally.  You do the same kind of
string pasting again.

You have the names in 'text', so you want to loop over that. Imagining
something like this:

fmt = "%s.%d.log"
for ligands in text:
    for suf in range(1, 11):
        filename = fmt % (ligand, suf)

or using f-strings:

        filename = f"{ligand}.{suf}"