Creating multiple files by changing values in a single file - python-3.x

Question

I have a file named myfile.txt given below:
&cntrl
pTopt = 298.15, pdens = 0.997, prcut = 12.0, pion = t,
pihot = t, prQM = 5.5, prSM = 5.3, prQI=3.0, piguess = f,
pinit = t, pnstep = 5000, pnscale = 100,
pnstat = 5, pnout = 5, pnrst = 5, pioutc = t, pioutv = t, pnoutc=5,
pnoutv = 5,
msolute = t, nosa = 1, pichrg = t
gfileOut = 'as-1.out',
gfileEnout = 'as-1.en',
gfileInfo = 'as-1.info',
gfileStart = 'init.in',
gfileRst = 'as-1.rst',
gfileTraj = 'as-1.traj',
gfileVeloc = 'as-1.vel',
gfileQmen = 'as-1.qmen'
&end
Using the above given single file I want to create 10 files but I want to manipulate the values of last eight variables in a way that value of the variable in every new file changes as the number of file changes i.e if ten files are created then the value of last eight variables like gfileOut in tength file should be 'as-10.out'.
For doing this I have a code given below:
#!/usr/bin/python3
for i in range(10):
f = open('file' +str(i)+'.txt','w')
f.write("&cntrl pTopt = 298.15, pdens = 0.997, prcut = 12.0,pion=t,"+"\n"+
"pihot = t, prQM = 5.5, prSM = 5.3, prQI=3.0, piguess = f,"+"\n"+
"pinit = t, pnstep = 5000, pnscale = 100,"+"\n"+"pnstat = 5, pnout = 5,
pnrst = 5, pioutc = t, pioutv = t, pnoutc = 5, pnoutv = 5,"+"\n"+
"msolute = t, nosa = 1, pichrg = t"+"\n"+'gfileOut = as-' +str(i)+ ".out,"+"\n"+
'gfileEnout = as-' +str(i)+ '.en,'+"\n"+'gfileInfo = as-' +str(i)+".info,"+"\n"+
'gfileStart = init' +str(i)+ ".in,"+"\n"+'gfileRst = as' +str(i)+ ".rst,"+"\n"+
'gfileTraj = as' +str(i)+ ".traj,"+"\n"
+'gfileVeloc = as' +str(i)+ ".vel,"+"\n"+'gfileQmen = as' +str(i)+ '.qmen'+"\n"+"&end ")
f.close()
The above given code produces right output but I want a way to read myfile.txt and change the values of last eight variables as mentioned above and then use this file to create ten new files.

Answer 1

str.format handles the inserts into the string to be written to each of the files.
# Write the files.
for i in range(1, 11):
with open('file' +str(i)+ '.txt','w') as f:
f.write(
('&cntrl pTopt = 298.15, pdens = 0.997, prcut = 12.0, pion=t,\n'
'pihot = t, prQM = 5.5, prSM = 5.3, prQI=3.0, piguess = f,\n'
'pinit = t, pnstep = 5000, pnscale = 100,\n'
'pnstat = 5, pnout = 5, pnrst = 5, pioutc = t, pioutv = t, pnoutc = 5, pnoutv = 5,\n'
'msolute = t, nosa = 1, pichrg = t\n'
'gfileOut = as-{index}.out,\n'
'gfileEnout = as-{index}.en,\n'
'gfileInfo = as-{index}.info,\n'
'gfileStart = init{index}.in,\n'
'gfileRst = as{index}.rst,\n'
'gfileTraj = as{index}.traj,\n'
'gfileVeloc = as{index}.vel,\n'
'gfileQmen = as{index}.qmen\n'
'&end ').format(index=i))
Note: The string contains {index} which is replaced by the value of i that range(1, 10) sets.
Edit: Re-done post due to misunderstanding the details of the question alerted by the 1st comment. Sorry.
Edit: Looked at need to read from file, so this may help.
template.txt:
&cntrl pTopt = 298.15, pdens = 0.997, prcut = 12.0, pion=t,
pihot = t, prQM = 5.5, prSM = 5.3, prQI=3.0, piguess = f,
pinit = t, pnstep = 5000, pnscale = 100,
pnstat = 5, pnout = 5, pnrst = 5, pioutc = t, pioutv = t, pnoutc = 5, pnoutv = 5,
msolute = t, nosa = 1, pichrg = t
gfileOut = as-{index}.out,
gfileEnout = as-{index}.en,
gfileInfo = as-{index}.info,
gfileStart = init{index}.in,
gfileRst = as{index}.rst,
gfileTraj = as{index}.traj,
gfileVeloc = as{index}.vel,
gfileQmen = as{index}.qmen
&end
main script:
# Read template file.
with open('template.txt') as r:
content = r.read()
# Write the files.
for i in range(1, 11):
with open('file' +str(i)+ '.txt','w') as f:
f.write(content.format(index=i))