help parsing file

[aslezak]

This is what I have so far. I'm not sure how robust it is

import csv
import tkinter as tk
from tkinter import filedialog
from math import *

root = tk.Tk()
root.withdraw()

#opened file must be NASTRAN input file. Check .nas extension
file_path = filedialog.askopenfilename()

nas = open(file_path ,mode = 'r', encoding = 'utf-8')

n=[]
x=[]
y=[]
z=[]
nextline = 0
for line in nas:
    if line[:4] == "GRID":
        nextline = 1
        n.append(line[8:8 + 16])
        x.append(line[8 + 2*16:8+3*16])
        y.append(line[8 + 3*16:8+4*16])
        continue    
    if nextline == 1:
        z.append(line[8:8+16])
        nextline = 0

def scientific(coord):
    ind = 0
    for i in coord:
        if i.find('+') > -1:
            coord[ind] = i.replace('+', 'E+')
        elif i.find('-') > -1:
            if i.find('-') == 0:
                s = i.lstrip('-')
                i = '-' + s.replace('-', 'E-')
            else:
                i = i.replace('-', 'E-')
            coord[ind] = i
        ind = ind + 1    

scientific(x)
scientific(y)
scientific(z)
        
with open('gridout.csv', 'w', newline='') as csvFile:
    writer = csv.writer(csvFile)
    index = 0
    for i in n:
        writer.writerow([n[index], x[index], y[index], z[index]])
        index = index + 1

nas.close()