创建多个* .cfg文件Python

Question

I'm working with *.cfg files. The file can be read in a text editor like gedit and has this format:

% some comments
VAR_1= 1
%
% More comments
ANOTHER_VAR= -8
%
% comments again
VAR_THE_COMEBACK= 10

I want to create multiple config files just changing VAR_1= 1....2...3.........10. I manage to import the *cfg file without any new import in python but I'm not getting a way to change just this parameter, saving the file and creating another one with another value for VAR_1.

my code until now is really simple:

import os

os.chdir('/home/leonardo/Desktop')

f = open('file.cfg','r') #if I replace r by w I erase the file ....
a =  f.read()
print a.find('1')
a.replace('1','2') #I tried this but. ... :(

f.close()

Any tips ?

Thank you for the help !

Answer 1

Untested code, but you will get the idea:

with open('file.cfg', 'r') as f:
    contents_by_line = f.readlines()
    for var_index, line in enumerate(contents_by_line):
        if line.startswith("VAR_"):
            break
    else:
        raise RuntimeError("VAR_ not found in file")

for var_i, new_cfg_file in ((2,"file2.cfg"),
                              (3, "file3.cfg")): #add files as you want
   with open(new_cfg_file, "w") as fout:
       for i, line in enumerate(contents_by_line):
           if i == var_index:
               fout.write("VAR_1=%d\n" % var_i)
           else:
               fout.write(line)

Answer 2

Thank you guys for all the help. I changed my approach to the problem, since the lines would be all the 'same', I just created a new line and replaced with a function I found here in stack. I hope it will help someone someday.

This script will automate a series of CFD simulations for my final project at college. It creates a series of folders with some simulation conditions on the name, copies the mesh file to the folder created as well as the new config file, the last line will run the code but I need to work in the base simulation setup to run the script.

The code is just in preliminary fase, I'll change it to be more readable and to be easily modified.

thank you guys ! Any tip is welcome, I'm trying to improve my coding skill : )

the code :::

import fileinput
import os
import shutil
import subprocess

class stuff:
    root_folder = '/home/leonardo/Desktop/testzone'
    mini_mach = 0.3
    maxi_mach = 1.3
    number_steps = 3
    increment = ((maxi_mach-mini_mach)/number_steps)
    config_file = 'inv_NACA0012.cfg'
    parameter_1 = 'MACH_NUMBER= 0.8'
    parameter_2 = 'CONV_NUM_METHOD_ADJFLOW= JST'
    init_pa = 'MACH_NUMBER= ' #use a space after '='
    init_pa2 = 'CONV_NUM_METHOD_ADJFLOW= ' #use a space after '='
    airfoil = 'NACA0012'
    command1 = 'parallel_computation.py -f ' #use space before the last " ' "
    command2 = '-n 2'
    mesh_file = 'mesh_NACA0012_inv.su2'

class modify:
     def replaceAll(self,files,searchExp,replaceExp):
         for line in fileinput.input(files, inplace=1):
            if searchExp in line:
                line = line.replace(searchExp,replaceExp)
            sys.stdout.write(line)

mod = modify()
stuff = stuff()

for i in xrange(stuff.number_steps):
    mach_name = stuff.airfoil + '_mach_' + `float('%.2f'% stuff.mini_mach)` 
    folder_name = stuff.root_folder + '/' + mach_name
    print 'creating ...' + folder_name
    os.makedirs(folder_name)
    file_father = stuff.root_folder + '/' + stuff.config_file 
    shutil.copy2(file_father,folder_name)
    mesh_father = stuff.root_folder + '/' + stuff.mesh_file
    shutil.copy2(mesh_father,folder_name)
    os.chdir(folder_name)
    pre_mod_file = mach_name + '.cfg'
    os.renames(stuff.config_file,pre_mod_file)
    new_parameter_1 = stuff.init_pa + `float('%.2f'% stuff.mini_mach)`
    new_parameter_2 = stuff.init_pa2 + `float('%.2f'% stuff.mini_mach)`
    mod.replaceAll(pre_mod_file,stuff.parameter_1,new_parameter_1)
    mod.replaceAll(pre_mod_file,stuff.parameter_2,new_parameter_2)
    stuff.mini_mach += stuff.increment
    #subprocess.check_call(stuff.command + pre_mod_file + stuff.command2)