Verify file names by standard

Question

I'm fairly new to python scripting and I want to verify file names in a directory and subdirectory. The verification should be case sensitive. I'm using python 2.6.5 OS: win7 and xp

I prompt for the following user input:

prompt = "year"
year = raw_input(prompt)
prompt = "number"
number = raw_input(prompt)

From here I want to search/verify that the following files and folders exist and their filename is correct.

folderstructure:

..\foobar_(number)_version1\music

Files in subfolder 'music'

(year)_foobar_(number)_isnice.txt
(year)_itis(number)hot_today.txt
(year)_anything_is(number)possible.txt
(year)_something_{idont_want_to_check_this_part}_(number)_canbe_anything.txt

Note that all text including underscores are always the same, and thus should always be right, except for the things between () or {}. I want to output the results to a txt file which reports if the filename is correct or not.

What is the most logical method to archieve this? I've read the lib documentation fnmatch(.fnmatchcase), RE and os(.path.isfile) and searched here for examples, but I just can't figure out where and how to start.

Can anyone point me in the right direction?

[edit] As soon as my script has the working basics I'll post my code for reference or to help others.

[edit2] my first non-hello world script

import os
import re

#output :
file_out = "H:\\output.txt"
f_out = open(file_out, 'w')

print "-------start-script----------"

#input
prompt = "enter 4 digit year: "
year = raw_input(prompt)
prompt = "enter 2 digit number: "
number = raw_input(prompt)

print "the chosen year is %s" % (year)
print "the chosen number is %s" % (number)

f_out.write ("start log!\n")
f_out.write ("------------------------------------------\n")
f_out.write ("the chosen year is %s\n" % (year))
f_out.write ("the chosen number is %s\n" % (number))

#part i'm working on

print "end script"
f_out.write ("------------------------------------------\n")
f_out.write ("end script\n")

#close file
f_out.close()

Answer 1

Take a look at the glob module - this will help you get a list of files in the current directory:

import glob

year = raw_input('Year: ')        # Example: Year: 2009
number = raw_input('Number: ')    # Example: Number: 12
filenames = glob.glob('{year}_*{number}*'.format(year=year, number=number))

Filenames will be anything in the current directory that meets the following criteria:

1. Begins with 2009_
2. Any number of characters until it matches 12
3. Any number of characters following 12.

os.path.exists is a good way to check if the file exists, or os.path.isfile if you want to make sure that it's really a file and not a directory named like a file. For Python3, check these docs, and like the link ghostbust555 mentioned says, be careful of race conditions if you plan on doing anything besides verifying their existence.

---

Based on your comment, it looks like this is a job for regular expressions. The pseudo code for what you need to write looks something like this:

for filename in list of filenames:
    if filename is not valid:
        print "<filename> is not valid!"

Aside from the actual pattern, the actual python code could look like this:

import os
import re

pattern = 'Put your actual pattern here'

# For a different directory, change the . to whatever the directory should be
for filename in os.listdir('.'):
    if not re.match(pattern, filename):
        print("Bad filename: ", filename)

Answer 2

This is not meant to be a full answer, but an extension of @Wayne Werner's answer. I don't have enough reputation points yet to comment. ;0

Wayne's approach using format I think is pointing to what you should do because it's validating filename BEFORE the files are built instead of after. And it seems that's what you're doing and have control over?

1. I would do as much validation at the user input level as possible.
2. Validate the other parts from whereever you get them.
3. Build a dictionary with the parts.
4. Build your file_name.

For example, at the user input level, something like:

yourDict = dict() 

year_input = raw_input('What is the year'?)

if not year_input.isdigit():  
    year_input = raw_input('Only digits please in the format YYYY, example: 2012'):

yourDict[year] = year_input

Then continute to add key:values to yourDict by validating the other values by whatever criteria it is you have. (Use re module or other method's mentioned).

Then, as Wayne was doing, use .format() with a passed in dictionary to map to the correct parts.

format1 = "{year}{part1}{number}{part2}.txt".format(**yourDict)

The approach also allows you to quickly build new formats with the same parts, and you can pick and choose what keys in the dictionary you need or don't need for each format.

Hope that's helpful.

Answer 3

import os.path

year = 2009
file1 = year + "_foobar_" + number + "_isnice.txt"

os.path.exists(file1)