Question

I have a file (with extension.hgx) that has some data like this:

length             =  0.00000783
height             =  48
RATIO              =  2
X                  =  1.0
Y                  =  1.0

I would like to open the file and replace the two lines:

---

height             =  48
RATIO              =  2

---

With:

---

height             =  8
RATIO              =  8

---

I tried parsing the file and could search for the “height” and “RATIO”. Unfortunately, I could not replace the line with new line and re-save the file. In my case the problem is that, that in the file the value of parameters e.g. height(=48) varies and sometimes has uneven spaces in between. I want to replace this complete line with–
height = 8

I have written the following code

import fileinput
import sys
f = open('test.hgx','r')
line_num = 0
search_phrase = "height"
for line in f.readlines():
    line_num += 1
    if line.find(search_phrase) >= 0:
        print line_num

newline='height                  =  8'
lnum=1
for line in fileinput.FileInput("test.hgx",inplace=1):
    if lnum==line_num:
        result = newline+"\n"
    else:
        result=line
    lnum=lnum+1    
    sys.stdout.write(result)
    print line

This does not help replace complete line and save the file again. returns empty file.Any help would be greatly appreciated.

Regards,
Ris

Answer 1

How’s this?

with open('test.hgx') as f:  lines = f.read().splitlines()
with open('test.hgx', 'w') as f:
  for line in lines:
    if line.startswith('height') or line.startswith('RATIO'):  
      f.write(line.rsplit(' ', 1)[0] + ' 8\n')
    else:
      f.write(line + '\n')