World's Best AI Learning Platform with profoundly Demanding Certification Programs
Designed by IITians, only for AI Learners.
Download our e-book of Introduction To Python
Related Blog
Top Discussion
USA(+256704300651)Top Powerful Love Spells That Really Work By Powerful Revenge Spell Caster in# Canada, #Australia #,UK,//USA Black magic IN >@>USA,/ UK,/ Kuwait,/ Germany, +256704300651--- …Extremely Powerful Death Spells Caster To Kill An Enemy With No Evidence / Ex Husband How can I write Python code to change a date string from "mm/dd/yy hh: mm" format to "YYYY-MM-DD HH: mm" format? +256704300651- Psychic lost love Spell Caster // Divorce Spell // Marriage Proposal A SPELL CASTER/╬ ₩௹]+256704300651₩௹]╬MAMA ZAMIE A TRADITIONAL HEALER /SANGOMA AND A SPIRITUAL HEALER in BELGIUM, +256704300651 == WASHINGTON DC// TOP DEATH SPELLS @POWERFUL REVENGE DEATH SPELL CASTER IN USA,CANADA, UK, CALIFONIA, MEXICO, IRELAND, NY, CANADA, LONDON, SWEDEN, BOTSWANA Exception Type: JSONDecodeError at /update/ Exception Value: Expecting value: line 1 column 1 (char 0) FORTUNER TELLER-(( +256704300651))- Most Effective death revenge Spells Caster USA, UK, BAHAMAS, BAHRAIN, NEW ZEALAND,SPAIN AUSTRALIA SOUTH SUDAN Join Discussion
Top Courses
Master's In Artificial Intelligence Job Guarantee Program
4.5 (1,292 Ratings)
559 Learners
Webinars
Live Masterclass on : "How Machine Get Trained in Machine Learning?"
Jun 1st (5:32 PM) 515 Registered
How to check if the file is existing or not in python
Shashank Shanu
3 years ago
Many times,
you may want to know how you can know what are the files already exist in a computer. So, the ability to check whether a file exists on
disk or not is an important task for many types of Python programs.
Let’s
take an example
Suppose,
you want to make sure a data file is available before you try to load it, or
you want to prevent overwriting an existing file. This is also true with
respect to directories where you try to ensure an output folder is available
before your program runs with an error.
Python
consist of several ways which help us to verify a file or directory exists using
some functions built using the core language and the Python standard library.
Here,
in this article, you’ll see different techniques for file existence checks in
Python.
Let’s
do it.
Method 1:
Using os.path.exists() and os.path.isfile()
Both
the above functions are available on Python 2 and Python 3.
Let’s take an example and understand how to work with the os.path.exists() function.
In the below example we are trying to check several paths such as files
and directories whether it exists or not.
import os.path
os.path.exists(“InsideAIML_directory/myfile.txt”)
output: true
os.path.exists(“myfile_copy.txt”)
output: false
os.path.exists(“InsideAIML_directory”)output: trueIn the above example we can see, when we try to call os.path.exists()
it return true for
files and directories
as both are present in the computer. And if the file or directory does not exist
it will return false.
We can use os.path.isfile()
function to ensure that a given path points to a file and
not to a directory.
import os.path
os.path.isfile (“InsideAIML_directory/myfile.txt”)
output: trueos.path.isfile (“myfile_copy.txt”)output: falseos.path.isfile (“InsideAIML_directory”)output: falseMethod 2:
Using open() and try...except
In the above example we just saw how both the functions in
the os.path module
can be used to check whether a file or a folder exist or not.
Here’s in python another straightforward algorithm is present for
checking whether a file exists. Here, we simply attempt to
open the file with the built-in open() function, which is given below-
Open(“myfile_copy.txt”)FileNotFoundError:
“[Errno 2] No such file or directory: ‘myfile_copy.txt’ ”
If the file exists in the given path the open method will complete successfully open the file
and return a valid filehandle. If the file does not exist, however, an
error FileNotFoundError exception
will be raised:
“FileNotFoundError is raised when a file or directory is
requested but doesn’t exist. Corresponds to errno ENOENT.” (Source: Python Docs)
This helps us to watch for this FileNotFoundError exception
type in our own code, and use it to detect whether a file exists or not. Below
is an example that will demonstrate this technique:
try:
file = open(“myfile.txt”)
file.close()
except FileNotFoundError:
print(“The given file does not exist”)
You may notice in the above example, how I’m immediately calling
the close() method
on the file, object to release the underlying filehandle. This
is generally considered a good practice when dealing with files in
Python:
If
we don’t close the filehandle explicitly as shown in the above example it is
difficult to know when exactly it will be closed automatically by the Python
runtime. It wastes system resources and can make our programs run less
efficiently.
In
python, another option is also available if we don’t want to close it
explicitly. We use the context manager protocol and the with a statement to auto-close the
file.
Now, the same “just attempt to open it” technique also works for
ensuring a file is both readable and accessible. Instead of watching for FileNotFoundError exceptions, you’ll want to
look out for any kind of IOError:
try:
file = open(“myfile.txt”)
file.close()
except IOError:
print(“You cannot access this file”)
print(“You can access this file”)
Now Let’s consider, if we want to use the above technique very frequently then we can create a helper function that will allow us to test whether a file exists and is accessible at the same time as shown below.
def file_accessible(path, mode= ’r’):
“””
Check if the file or directory at “path” can
be accessed by the program using the “mode”
open plays equal to reading mode (r).
“””
try:
file = open(path, mode)
file.close()
except IOError:
return false
return true
In python, there are many more techniques available for handling
different types of file. But, in this article, I only explained to you about two
such techniques.
Now if you are planning to deal with a file in python afterwards, I
would recommend that you do the existence check via the open() method and exception handling. This will
help us to code better.
I hope after you enjoyed reading this article and finally,
you came to know about How to work with the file in python.
For more such blogs/courses on data science, machine
learning, artificial intelligence and emerging new technologies do visit us at InsideAIML.