Checking file extension

问题:

I'm working on a certain program and I need to have it do different things if the file in question is a flac file, or an mp3 file. Could I just use this?

if m == *.mp3
   ....
elif m == *.flac
   ....

I'm not sure whether it will work.

EDIT: When I use that, it tells me invalid syntax. So what do I do?

回答1:

Assuming m is a string, you can use endswith:

if m.endswith('.mp3'):
...
elif m.endswith('.flac'):
...

To be case-insensitive, and to eliminate a potentially large else-if chain:

m.lower().endswith(('.png', '.jpg', '.jpeg'))

(Thanks to Wilhem Murdoch for the list of args to endswith)

回答2:

os.path provides many functions for manipulating paths/filenames. (docs)

os.path.splitext takes a path and splits the file extension from the end of it.

import os

filepaths = ["/folder/soundfile.mp3", "folder1/folder/soundfile.flac"]

for fp in filepaths:
    # Split the extension from the path and normalise it to lowercase.
    ext = os.path.splitext(fp)[-1].lower()

    # Now we can simply use == to check for equality, no need for wildcards.
    if ext == ".mp3":
        print fp, "is an mp3!"
    elif ext == ".flac":
        print fp, "is a flac file!"
    else:
        print fp, "is an unknown file format."

Gives:

/folder/soundfile.mp3 is an mp3!
folder1/folder/soundfile.flac is a flac file!

回答3:

Look at module fnmatch. That will do what you're trying to do.

import fnmatch
import os

for file in os.listdir('.'):
    if fnmatch.fnmatch(file, '*.txt'):
        print file

回答4:

or perhaps:

from glob import glob
...
for files in glob('path/*.mp3'): 
  do something
for files in glob('path/*.flac'): 
  do something else

回答5:

one easy way could be:

import os

if os.path.splitext(file)[1] == ".mp3":
    # do something

os.path.splitext(file) will return a tuple with two values (the filename without extension + just the extension). The second index ([1]) will therefor give you just the extension. The cool thing is, that this way you can also access the filename pretty easily, if needed!

回答6:

import os
source = ['test_sound.flac','ts.mp3']

for files in source:
   fileName,fileExtension = os.path.splitext(files)
   print fileExtension   # Print File Extensions
   print fileName   # It print file name

回答7:

if (file.split(".")[1] == "mp3"):
    print "its mp3"
elif (file.split(".")[1] == "flac"):
    print "its flac"
else:
    print "not compat"

回答8:

#!/usr/bin/python

import shutil, os

source = ['test_sound.flac','ts.mp3']

for files in source:
  fileName,fileExtension = os.path.splitext(files)

  if fileExtension==".flac" :
    print 'This file is flac file %s' %files
  elif  fileExtension==".mp3":
    print 'This file is mp3 file %s' %files
  else:
    print 'Format is not valid'

回答9:

An old thread, but may help future readers...

I would avoid using .lower() on filenames if for no other reason than to make your code more platform independent. (linux is case sensistive, .lower() on a filename will surely corrupt your logic eventually ...or worse, an important file!)

Why not use re? (Although to be even more robust, you should check the magic file header of each file... How to check type of files without extensions in python? )

import re

def checkext(fname):   
    if re.search('\.mp3$',fname,flags=re.IGNORECASE):
        return('mp3')
    if re.search('\.flac$',fname,flags=re.IGNORECASE):
        return('flac')
    return('skip')

flist = ['myfile.mp3', 'myfile.MP3','myfile.mP3','myfile.mp4','myfile.flack','myfile.FLAC',
     'myfile.Mov','myfile.fLaC']

for f in flist:
    print "{} ==> {}".format(f,checkext(f)) 

Output:

myfile.mp3 ==> mp3
myfile.MP3 ==> mp3
myfile.mP3 ==> mp3
myfile.mp4 ==> skip
myfile.flack ==> skip
myfile.FLAC ==> flac
myfile.Mov ==> skip
myfile.fLaC ==> flac

回答10:

Use pathlib From Python3.4 onwards.

from pathlib import Path
Path('my_file.mp3').suffix == '.mp3'