Vtyjkyuk

I am a Python beginner and looking for help with an extraction problem.

I have a bunch of textfiles and need to extract all special combinations of an expression ("C"+"exactly 9 numerical digits") and write them to a file including the filename of the textfile. Each occurence of the expression I want to catch start at the beginning of a new line and ends with a "/n".

sample_text = """Some random text here 
and here
and here
C123456789
some random text here
C987654321
and here
and here"""

What the output should look like (in the output file)

My_desired_output_file = "filename,C123456789,C987654321"

My code so far:

min_file_size = 5

def list_textfiles(directory, min_file_size): # Creates a list of all files stored in DIRECTORY ending on '.txt'
 textfiles = 
 for root, dirs, files in os.walk(directory):
 for name in files:
 filename = os.path.join(root, name)
 if os.stat(filename).st_size > min_file_size:
 textfiles.append(filename)

for filename in list_textfiles(temp_directory, min_file_size): 
 string = str(filename)
 text = infile.read()
 regex = ???
 with open(filename, 'w', encoding="utf-8") as outfile:
 outfile.write(regex)

your regex is '^C[0-9]9$'

^ start of line
C exact match
[0-9] any digit
9 9 times
$ end of line

import re

regex = re.compile('(^Cd9)')
matches = 
with open('file.txt', 'r') as file:
 for line in file:
 line = line.strip()
 if regex.match(line):
 matches.append(line)

You can then write this list to a file as needed.

How about:

import re

sample_text = """Some random text here 
and here
and here
C123456789
some random text here
C987654321
and here
and here"""

k = re.findall('(Cd9)',sample_text)

print(k)

This will return all occurrences of that pattern. If you yield line from your text and store your target combination. Something like:

Updated:

import glob
import os
import re

search = 
os.chdir('/FolderWithTxTs')
for file in glob.glob("*.txt"):
 with open(file,'r') as f:
 data = [re.findall('(Cd9)',i) for i in f]
 search.update(f.name:data)

print(search)

This would return a dictionary with file names as keys and a list of found matches.