replacing specific lines in a text file using python - python-2.7

Question

First of all I am pretty new at python, so bear with me. I am attempting to read from one file, retrieve specific values and overwrite old values in another file with a similar format. The format is 'text value=xxx' in both files. I have the first half of the program working, I can extract the values I want and have placed them into a dict named 'params{}'. The part I haven't figured out is how to just write the specific value into the target file without it showing up at the end of the file or just writing garbage or only half of the file. Here is my source code so far:
import os, os.path, re, fileinput, sys
#set the path to the resource files
#res_files_path = r'C:\Users\n518013\Documents\203-104 WA My MRT Files\CIA Data\pelzer_settings'
tst_res_files_path = r'C:\resource'
# Set path to target files.
#tar_files_path = r'C:\Users\n518013\Documents\203-104 WA My MRT Files\CIA Data\CIA3 Settings-G4'
tst_tar_files_path = r'C:\target'
#test dir.
test_files_path = r'C:\Users\n518013\Documents\MRT Equipment - BY 740-104 WA\CIA - AS\Setting Files\305_70R_22_5 setting files\CIA 1 Standard'
# function1 to find word index and point to value
def f_index(lst, item):
ind = lst.index(item)
val = lst[ind + 3]
print val
return val
# function 2 for values only 1 away from search term
def f_index_1(lst, item):
ind = lst.index(item)
val = lst[ind + 1]
return val
# Create file list.
file_lst = os.listdir(tst_res_files_path)
# Traverse the file list and read in dim settings files.
# Set up dict.
params = {}
#print params
for fname in file_lst:
file_loc = os.path.join(tst_res_files_path, fname)
with open(file_loc, 'r') as f:
if re.search('ms\.', fname):
print fname
break
line = f.read()
word = re.split('\W+', line)
print word
for w in word:
if w == 'Number':
print w
params['sectors'] = f_index(word, w)
elif w == 'Lid':
params['lid_dly'] = f_index(word, w)
elif w == 'Head':
params['rotation_dly'] = f_index(word, w)
elif w == 'Horizontal':
tmp = f_index_1(word, w)
param = int(tmp) + 72
params['horizontal'] = str(param)
elif w == 'Vertical':
tmp = f_index_1(word, w)
param = int(tmp) - 65
params['vertical'] = str(param)
elif w == 'Tilt':
params['tilt'] = f_index_1(word, w)
else:
print 'next...'
print params #this is just for debugging
file_tar = os.path.join(tst_tar_files_path, fname)
for lines in fileinput.input(file_tar, inplace=True):
print lines.rstrip()
if lines.startswith('Number'):
if lines[-2:-1] != params['sectors']:
repl = params['sectors']
lines = lines.replace(lines[-2:-1], repl)
sys.stdout.write(lines)
else:
continue
Sample text files:
[ADMINISTRATIVE SETTINGS]
SettingsType=SingleScan
DimensionCode=
Operator=
Description=rev.1 4sept03
TireDimClass=Crown
TireWidth=400mm
[TEST PARAMETERS]
Number Of Sectors=9
Vacuum=50
[DELAY SETTINGS]
Lid Close Delay=3
Head Rotation Delay=3
[HEAD POSITION]
Horizontal=140
Vertical=460
Tilt=0
[CALIBRATION]
UseConvFactors=0
LengthUnit=0
ConvMMX=1
ConvPixelX=1
CorrFactorX=1
ConvMMY=1
ConvPixelY=1
CorrFactorY=1
end sample txt.
The code I have only writes about half of the file back, and I don't understand why? I am trying to replace the line 'Number of Sectors=9' with 'Number of Sectors=8' if I could get this to work, the rest of the replacements can be done using if statements.
Please help! I've spent hours on google looking for answers and info and everything I find gets me close but no cigar!
Thank you all in advance!

Answer 1

your file has the '.ini' format. python supports reading and writing those with the ConfigParser module. you could do this:
# py3: from pathlib import Path
import os.path
import configparser
# py3: IN_PATH = Path(__file__).parent / '../data/sample.ini'
# py3: OUT_PATH = Path(__file__).parent / '../data/sample_out.ini'
HERE = os.path.dirname(__file__)
IN_PATH = os.path.join(HERE, '../data/sample.ini')
OUT_PATH = os.path.join(HERE, '../data/sample_out.ini')
config = configparser.ConfigParser()
# py3: config.read(str(IN_PATH))
config.read(IN_PATH)
print(config['CALIBRATION']['LengthUnit'])
config['CALIBRATION']['LengthUnit'] = '27'
# py3: with OUT_PATH.open('w') as fle:
with open(OUT_PATH, 'w') as fle:
config.write(fle)