Python Tutorial - fnmatch module

Python Exercise Lists

For Filename Matching in Python

The fnmatch module is mainly used for file name matching. Its ability is more powerful than simple string matching, but slightly weaker than using regular expressions. If you only need to use simple wildcards to complete file name matching in data processing operations, using the fnmatch module is a good choice.

The following table shows the commonly used functions and their functions in the fnmatch module.

The fnmatch module uses the UNIX shell style to match filenames. It supports the following wildcards:

• *: Can match any number of any characters.
• ? : Matches any arbitrary character.
• [Character Sequence]: Can match any character in the character sequence in brackets. This character sequence also supports midline line notation. For example, [a-c] can represent any of the a, b, and c characters.
• [! Character sequence]: matches any character that is not in the character sequence in the brackets.

For example, the following program demonstrates the usage and function of some functions in Table above:

import fnmatch
#filter()
print(fnmatch.filter(['dlsf', 'ewro.txt', 'te.py', 'youe.py'], '*.txt'))
#fnmatch()
for file in ['word.doc','index.py','my_file.txt']:
    if fnmatch.fnmatch(a,'*.txt'):
        print(file)
#fnmatchcase()
print([addr for addr in ['word.doc','index.py','a.txt','a.TXT'] if fnmatch.fnmatchcase(addr, '*.txt')])
#translate()
print(fnmatch.translate('a*b.txt'))
           

The output is:

['ewro.txt']
my_file.txt
['a.txt']
(?s:a.*b\.txt)\Z

Python Tempfile Module

Generate temporary files and temporary directories. The tempfile module is designed to create temporary files and temporary directories. It works well on both UNIX platforms and Windows platforms.

Functions commonly used in the tempfile module are shown in the following table.

The tempfile module also provides two low-level functions, tempfile.mkstemp () and tempfile.mkdtemp (). The four functions described above for creating temporary files and temporary directories are high-level functions. High-level functions support automatic cleanup and can be used with the with statement. These two low-level functions are not supported. Therefore, it is generally recommended to use high-level functions to create temporary files and temporary directories.

In addition, the tempfile module also provides the tempfile.tempdir property. You can change the system's temporary directory by assigning a value to this property.

The following program demonstrates how to use temporary files and temporary directories:

import tempfile
# Create temporary file
fp = tempfile.TemporaryFile ()
print (fp.name)
fp.write ('Python Website,' .encode ('utf-8'))
fp.write ('shows some tutorials.'. encode ('utf-8'))
# Move the file pointer to the beginning, ready to read the file
fp.seek (0)
print (fp.read (). decode ('utf-8')) # print the content just written
# Close the file, the file will be deleted automatically
fp.close ()
# Create a temporary file with the with statement, with will automatically close the temporary file
with tempfile.TemporaryFile () as fp:
    # Write content
    fp.write (b'I Love Python! ')
    # Move the file pointer to the beginning, ready to read the file
    fp.seek (0)
    # Read file contents
    print (fp.read ()) # b'I Love Python! '
# Create a temporary directory with the with statement
with tempfile.TemporaryDirectory () as tmpdirname:
    print ('Create temporary directory', tmpdirname)
           

The output is:

C:\Users\LIM~1.JOU\AppData\Local\Temp\tmpt86_3m5v
Python Website,shows some tutorials.
b'I Love Python! '
Create temporary directory C:\Users\LIM~1.JOU\AppData\Local\Temp\tmpaivr821d

The above program creates temporary files in two ways:

The first method is to manually create a temporary file. After reading and writing the temporary file, you need to actively close it. When the program closes the temporary file, the file will be automatically deleted.

The second way is to use a with statement to create a temporary file so that the with statement automatically closes the temporary file.

The above program also finally created a temporary directory. Because the program uses a with statement to manage the temporary directory, the program also automatically deletes the temporary directory.

The output of the first line above is the file name of the temporary file generated by the program, and the output of the last line is the directory name of the temporary directory generated by the program. It should be noted that do not look for temporary files or temporary folders, because the temporary files and temporary folders will be deleted when the program exits.