How to remove duplicate exception error in python try/except block?

Question

I am a new python programmer and have been making a file sort function to take a file name and neatly arrange it in a file structure being year/month/day. The following code works but looks ugly and there is a lot of duplicate exception errors which I would like to remove. Would love to see how to improve the efficiency of this code as it will be run frequently. Thanks in advance

def fileSort(day, month, year, file):
    global filewritten

    try: os.makedirs(togoto + '/' + year)
    except FileExistsError:
        pass
    try: os.makedirs(togoto + '/' + year + '/' + month)
    except FileExistsError:
        pass
    try:
        os.makedirs(togoto + '/' + year + '/' + month + '/' + day)
    except FileExistsError:
    pass
    try:
        shutil.move(path + '/' + file,
                    togoto + '/' + year + '/' + month + '/' + day + '/' + file)
        filewritten += 1

    except FileExistsError:
        pass

You could make a decision block seeing if each directory exists using os.path.isdir starting with the longest path for the first check and moving backwards. If the directory already exists, it would decrease your work. — I Funball
– I Funball, Commented Mar 6, 2019 at 16:11

glglgl · Accepted Answer · 2019-03-06 16:11:51Z

1

os.makedirs() already creates the directories leading to the given path, so it should be enough to do

try:
    os.makedirs(togoto + '/' + year + '/' + month + '/' + day)
except FileExistsError:
    pass
try:
    shutil.move(path + '/' + file,
                togoto + '/' + year + '/' + month + '/' + day + '/' + file)
    filewritten += 1

except FileExistsError:
    pass

This is a bit of an improvement to your original version.

BTW, os.path.join() is your friend:

source = os.path.join(path, file)
targetdir = os.path.join(togoto, year, month, day)
target = os.path.join(togoto, year, month, day, file)
try:
    os.makedirs(targetdir)
except FileExistsError:
    pass
try:
    shutil.move(source, target)
    filewritten += 1

except FileExistsError:
    pass

Even better would be to use all the capabilities of os.makedirs() if your Python is new enough:

source = os.path.join(path, file)
targetdir = os.path.join(togoto, year, month, day)
target = os.path.join(targetdir, file)

os.makedirs(targetdir, exist_ok=True) # i. e. no exception on an already existing path.
try:
    shutil.move(source, target)
    filewritten += 1
except FileExistsError:
    pass

answered Mar 6, 2019 at 16:11

glglgl

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1 Comment

rup Over a year ago

Ah wow that is so much neater. Thanks a lot, much appreciated!

Antti Haapala · Accepted Answer · 2019-03-06 16:14:14Z

1

First of all: use makedirs with only the innermost directory:

try: 
    os.makedirs(togoto + '/' + year + '/' + month + '/' + day)
except FileExistsError:
    pass

Then notice that you should probably use os.path.join to form the path instead, hence:

try: 
    os.makedirs(os.path.join(togoto, year, month, day))
except FileExistsError:
    pass

And... in Python 3 (3.2+) there is a parameter exists_ok that can be set to True so that no exception is thrown if the leaf child directory exists, so we get

os.makedirs(os.path.join(togoto, year, month, day), exists_ok=True)

Finally do note that shutil.move might - or might not - throw a FileExistsError if the target exists...

answered Mar 6, 2019 at 16:14

Antti Haapala

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Comments

Djaouad · Accepted Answer · 2019-03-06 16:15:27Z

1

You could define your own function to shorten the code and it's also good for re-usability:

def create_dir(name):
    try:
        os.makedirs(name)
    except FileExistsError:
        pass

def fileSort(day, month, year, file):
    global filewritten
    create_dir(togoto + '/' + year)
    create_dir(togoto + '/' + year + '/' + month)
    create_dir(togoto + '/' + year + '/' + month + '/' + day)
    try:
        shutil.move(path + '/' + file, togoto + '/' + year + '/' + month + '/' + day + '/' + file)
        filewritten += 1
    except FileExistsError:
        pass

edited Mar 6, 2019 at 16:15

answered Mar 6, 2019 at 16:11

Djaouad

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