Why are my files in in my list - os module used with sys argv
Peter Otten
__peter__ at web.de
Tue Apr 19 04:16:28 EDT 2016
Steven D'Aprano wrote:
> On Tue, 19 Apr 2016 09:44 am, Sayth Renshaw wrote:
>
>> Hi
>>
>> Why would it be that my files are not being found in this script?
>
> You are calling the script with:
>
> python jqxml.py samples *.xml
>
> This does not do what you think it does: under Linux shells, the glob
> *.xml will be expanded by the shell. Fortunately, in your case, you have
> no files in the current directory matching the glob *.xml, so it is not
> expanded and the arguments your script receives are:
>
>
> "python jqxml.py" # not used
>
> "samples" # dir
>
> "*.xml" # mask
>
>
> You then call:
>
> fileResult = filter(lambda x: x.endswith(mask), files)
>
> which looks for file names which end with a literal string (asterisk, dot,
> x, m, l) in that order. You have no files that match that string.
>
> At the shell prompt, enter this:
>
> touch samples/junk\*.xml
>
> and run the script again, and you should see that it now matches one file.
>
> Instead, what you should do is:
>
>
> (1) Use the glob module:
>
> https://docs.python.org/2/library/glob.html
> https://docs.python.org/3/library/glob.html
>
> https://pymotw.com/2/glob/
> https://pymotw.com/3/glob/
>
>
> (2) When calling the script, avoid the shell expanding wildcards by
> escaping them or quoting them:
>
> python jqxml.py samples "*.xml"
(3) *Use* the expansion mechanism provided by the shell instead of fighting
it:
$ python jqxml.py samples/*.xml
This requires that you change your script
from pyquery import PyQuery as pq
import pandas as pd
import sys
fileResult = sys.argv[1:]
if not fileResult:
print("no files specified")
sys.exit(1)
for file in fileResult:
print(file)
for items in fileResult:
try:
d = pq(filename=items)
except FileNotFoundError as e:
print(e)
continue
res = d('nomination')
# you could move the attrs definition before the loop
attrs = ('id', 'horse')
# probably a bug: you are overwriting data on every iteration
data = [[res.eq(i).attr(x) for x in attrs] for i in range(len(res))]
I think this is the most natural approach if you are willing to accept the
quirk that the script tries to process the file 'samples/*.xml' if the
samples directory doesn't contain any files with the .xml suffix. Common
shell tools work that way:
$ ls samples/*.xml
samples/1.xml samples/2.xml samples/3.xml
$ ls samples/*.XML
ls: cannot access samples/*.XML: No such file or directory
Unrelated: instead of working with sys.argv directly you could use argparse
which is part of the standard library. The code to get at least one file is
import argparse
parser = argparse.ArgumentParser()
parser.add_argument("files", nargs="+")
args = parser.parse_args()
print(args.files)
Note that this doesn't fix the shell expansion oddity.
More information about the Python-list
mailing list