how to use list elements as input to file open?

Question

For the SO admin/mods.

This question was marked closed as a duplicate to this question: How to read a file line-by-line into a list?

What a hoot. That isn't related to this question EXCEPT that it also involves a list. Didja bother to read the question?

Python 3 and 2.7.8.

I have a script that gets parsed into chunks based on the existence of a keyword. The argv after keyword is the file to process. All arguments up to the keyword are put into a list (inp_to_process). All files are simple ascii and are located in the current folder.

I want to open the files contained in the list, and my script fails. I am doing the same thing to open the file specified after the keyword, so I assume my issue has to do with using list elements as arguments.

I'm not able to do m for in list, nor can I use a range - both throw an exception trying to open the files given.

This single one works: try: with open(f_target) as FT: content_target = [line.rstrip('\n') for line in FT] except: # currently seems to print the parens too..

print ('Error! Unable to open file', f_target)
exit()

Here's the chunk of code doing the work (currently broken) both methods:

    for x in range(0, len(inp_to_process)):
    print (inp_to_process[x])
    try:
        with open (inp_to_process[x], "t") as d_input:
            data = d_input.read()
            print (len(data))
    except:
       print ('Error processing input file ' + inp_to_process[x])
exit()

and

   for m in inp_to_process:
   ifile = m
   try:
        print ('trying: ' + ifile)
        with open (ifile, "t") as d_input:
        print ('after open()')
            data = d_input.read()
            print (len(data))
            # content = [line.rstrip('\n') for line in d_input]
            # if not content in all_inp:
            #    all_inp.add(content)
   except:
       print ('Error processing input file ' + m)

So how can I access the list elements such they work in the open file command??

Thanks!

score 0 · Answer 1 · answered Nov 09 '21 at 17:07

OK, after a colleague figured this out, I have working code:

for num in inp_to_process[:]:
try:
    with open(num, "r") as f:
        content = [line.rstrip('\n') for line in f]
        print ('data length: ', str(len(content)), num)
except:
   print ('Error processing input file ' + num)

This parses the list and opens the files specified as desired. Cheers!

how to use list elements as input to file open?

1 Answers1