Can you please explain what the part after import sys is doing?

[Pedroski55]

Actually, I'm only trying to use the Python wc module to count words in a text file.

wc('/proc/cpuinfo') works nicely in Idle!

But I found this and I am trying to understand it!

I got this from https://code-maven.com/python-wc

It is about using wc (not the toilet )

We have the function:

def wc(*filenames):
    results = {}
    for filename in filenames:
        chars = 0
        words = 0
        lines = 0
        try:
            with open(filename) as fh:
                for line in fh:
                    lines += 1
                    words += len(line.split())
                    chars += len(line)
            results[filename] = {
                'lines': lines,
                'words': words,
                'chars': chars,
            }
        except Exception as err:
            print(err)
    return results

Then the main part, which I can't follow. Can you please explain it to me??

if __name__ == '__main__':
    import sys
    if len(sys.argv) < 1:
        exit("Usage: {} FILENAMEs".format(sys.argv[0]))
    results = wc(*sys.argv[1:])
    totals = {
        'lines': 0,
        'words': 0,
        'chars': 0,
    }
    for filename in results:
        res = results[filename]
        print("{} {} {} {}".format(res['lines'], res['words'], res['chars'], filename))
        for k in res:
            totals[k] += res[k]
    print("{} {} {} {}".format(totals['lines'], totals['words'], totals['chars'], 'total'))

How this main part supposed to know where the files are? Which files?

I made the above code, both parts, into a function, myApp() If I run myApp() in Idle I get:

>>> myApp()

0 0 0 total
>>>

My path is:

path = '/home/pedro/winter2020/20PY/dumpFiles/'

I thought, if I just pass it a list, the "splat" would open the list and the function would do the job, but I get an error.

>

>> myresults = wc(pathtoFiles)

expected str, bytes or os.PathLike object, not list

I got the files:

files = os.listdir(path)

Then ran this to get a list of path + file:

for file in files:      
    getFile = os.path.join(path, file)    
    if os.path.isdir(getFile): # this checks if file is a folder
        continue # don't get folders, use continue
    else:
        pathtoFiles.append(getFile)

I have a nice list of path + filename, but the function wc() above doesn't like this. Why is that?

[bowlofred]

These are some of the crucial lines...

    if len(sys.argv) < 1:
        exit("Usage: {} FILENAMEs".format(sys.argv[0]))

This is assuming that it's running as a command-line program, not just a function. It's looking at sys.argv, which has the arguments the program was run with. If you don't give it any (sys.argv has only the python program), then it exits with a usage message.

    results = wc(*sys.argv[1:])

It takes all the passed in arguments and passes those on to wc. So if you call your script from the command shell like:

C:\> myscript file1 file2

Then wc is called with the argument list ["file1", "file2"].

[Pedroski55]

Thanks!

How can I pass my list pathtoFiles to it?

I was hoping
def wc(*filenames):

would splat open the list and process it. But no!

pathtoFiles looks like this:

['/home/pedro/winter2020/20PY/dumpFiles/shikai_capital_letters.txt', '/home/pedro/winter2020/20PY/dumpFiles/Youjie_info.txt', '/home/pedro/winter2020/20PY/dumpFiles/info1_3.txt', '/home/pedro/winter2020/20PY/dumpFiles/capital_letters.txt', '/home/pedro/winter2020/20PY/dumpFiles/1926070127capital_letters.txt', '/home/pedro/winter2020/20PY/dumpFiles/PEOPLE.txt', '/home/pedro/winter2020/20PY/dumpFiles/123.txt', '/home/pedro/winter2020/20PY/dumpFiles/information.txt', '/home/pedro/winter2020/20PY/dumpFiles/info1.txt', '/home/pedro/winter2020/20PY/dumpFiles/1923010312capital_letters.txt', '/home/pedro/winter2020/20PY/dumpFiles/调查结果.txt', '/home/pedro/winter2020/20PY/dumpFiles/info1_1.txt', '/home/pedro/winter2020/20PY/dumpFiles/1929050140capital_letters.txt', '/home/pedro/winter2020/20PY/dumpFiles/chocolate_snow_in_Switzerland.txt', '/home/pedro/winter2020/20PY/dumpFiles/infol.txt']

[bowlofred]

The * in the call means that it is expanding the list into the individual elements. You can do the same for your list.

results = wc(*pathtoFiles)

wc is expecting something that looks like a filename (either a string or a Path object). But pathtoFiles is a list, so we have to open it up and just hand it the parts of the list, not the list itself.