Advanced write in a TXT file

This is not right related to Pandas, but it is very useful to store some special note to remember during a data process, and automate it.

Create/replace a TXT file and write something into

Use the Write option (w):

MyTxtFile = 'C:/_gh/0/My beautiful file.txt'
 
with open(MyTxtFile, 'w') as file:
    file.write('Blablabla...\n')
    file.write(MyVariable)

Add some lines in an existing file

Use the Append option (a):

MyTxtFile = 'C:/_gh/0/My beautiful file.txt'
 
with open(MyTxtFile, 'a') as file:
    file.write('Blablabla...\n')
    file.write(MyVariable)

Replace some lines in an existing file

Here we first Read (r option) and store the content of the file, and then re-create it removing the lines we would delete:

MyTxtFile = 'C:/_gh/0/My beautiful file.txt'
 
with open(MyTxtFile, 'r') as f:
    lines = f.readlines()
 
with open(MyTxtFile, 'w') as f:
    for line in lines:
        if not line.strip('\n').startswith('First line to delete...') :
            if not line.strip('\n').startswith('Second line to delete...') :
                if not line.strip('\n').startswith('Third line to delete...') :
                    f.write(line)
 
with open(MyTxtFile, 'a') as file:
    file.write('New line 1')
    file.write('New line 2')
    file.write('New line 3')

Replace a simple string in a TXT file

MyTxtFile = 'C:/_gh/0/My beautiful file.txt'
 
with open(MyTxtFile, 'r') as file :
    filedata = file.read()
 
filedata = filedata.replace('String 1', 'String 2')
 
with open(MyTxtFile, 'w') as file:
    file.write(filedata)

Replace a string with a regular expression (regex) in a TXT file

FichierTest = 'C:/_gh/0/FichierTest.txt'
 
import re
 
# Find number : r'[0-9]'
# Find line break : r'[\n]'
# Find double line break : r'[\r\n]{2,}'
 
with open(FichierTest, 'r+') as file:
    text = file.read()
    text = re.sub(r'[\r\n]{2,}', '\n\n', text)
    file.seek(0, 0) # seek to beginning
    file.write(text)
    file.truncate() # get rid of any trailing characters

Test if a comma is used as decimal separator in a TXT file

with open(MyTxtFile, 'r') as myfile:
    data = myfile.read()
    pb_regex = re.findall(r'(?:\t|^)\d+\K,(?=\d+(?:\t|$))', data)
    if pb_regex:
        print(colored('\nAttention, comma is used as a decimal separator in numeric value!\n' +
        'Find them in Notepad with:\n(?:\\t|^)\d+\K,(?=\d+(?:\\t|$))', 'yellow'))
    else:
        pass