[PYTHON] pathlib Are you all using it?

Introduction

** pathlib ** Do you use it? If you haven't used it yet, please use it once. What is pathlib is that you can manipulate paths. I think everyone uses ** os.path **, but you can do almost the same thing as that os.path with ** pathlib **. Moreover, pathlib is a standard Python module.

Who is the target of this article

--Those who have never used pathlib --People who know pathlib but haven't made it yet --Those who are interested in pathlib

If you are interested, please check it out.

summary

--Get file name only ** filename.name ** --Get filename without extension ** filename.stem ** --File extension only ** filename.suffix ** --Read file ** list (dir_path.iterdir ()) **, ** list (dir_path.glob ('*')) ** --Create directory (also intermediate directory) ** dir_path.mkdir (parents = True) ** --Create directory (no error even if it exists) ** dir_path.mkdir (exist_ok = True) ** --Create new file ** filename.touch () **

pathlib

pathlib is a ** object-oriented file system path **. Let's see how to use it.

constructor

You can create a Path object withPath ()

>>> from pathlib import Path
>>> Path()
PosixPath('.')
>>> Path('data')
PosixPath('data')
>>> 

>>> Path('data/image_0001.jpg')
PosixPath('data/image_0001.jpg')
>>> 

Determining whether it is a directory or a file

Use ʻis_dir (), ʻis_file ()

>>> a = Path('data')
>>> a.is_dir()
True
>>> b = Path('data/image_0001.jpg')
>>> b.is_file()
True
>>> 

Check for non-existent files

>>> p = Path('data/img0.jpg')
>>> p.exists()
False

Create empty file

Use .touch ()

>>> p = Path('data/img0.jpg')
>>> p.exists()
False
>>> p.touch()
>>> p.exists()
True

Get a list of files directly under the directory

Use ʻiterdir () or glob () `

>>> a = Path('data')
>>> list(a.iterdir())
[PosixPath('data/img0.jpg'), 
PosixPath('data/image_0004.jpg'),
PosixPath('data/image_0005.jpg'), 
PosixPath('data/image_0001.jpg'), 
PosixPath('data/image_0002.jpg'), 
PosixPath('data/image_0003.jpg')]
>>> 


>>> list(a.glob('*'))
[PosixPath('data/img0.jpg'), 
PosixPath('data/image_0004.jpg'), 
PosixPath('data/image_0005.jpg'), 
PosixPath('data/image_0001.jpg'), 
PosixPath('data/image_0002.jpg'), 
PosixPath('data/image_0003.jpg')]
>>> 

Convert all file names to strings

Convert to a string with str

>>> [str(p) for p in a.iterdir()]
['data/img0.jpg', 
'data/image_0004.jpg', 
'data/image_0005.jpg', 
'data/image_0001.jpg', 
'data/image_0002.jpg', 
'data/image_0003.jpg']
>>> 

Get only the file name (at the end of the path)

Use the name attribute

>>> [p.name for p in a.iterdir() if p.is_file()]
['img0.jpg', 
'image_0004.jpg', 
'image_0005.jpg', 
'image_0001.jpg', 
'image_0002.jpg', 
'image_0003.jpg']
>>> 

Get file name without extension

Use the stem attribute

>>> [p.stem for p in a.iterdir() if p.is_file()]
['img0', 
'image_0004', 
'image_0005', 
'image_0001', 
'image_0002', 
'image_0003']
>>> 

Get the file name extension

Use the shuffix attribute

>>> [p.suffix for p in a.iterdir() if p.is_file()]
['.jpg', '.jpg', '.jpg', '.jpg', '.jpg', '.jpg']
>>> 

Creating a directory

Use .mkdir ()

>>> c = Path('test')
>>> c.exists()
False
>>> c.mkdir()
>>> c.exists()
True
>>> 

Create intermediate directories together

Set to parents = True

>>> Path('test/data/001').mkdir(parents=True)

Don't get an error even if the directory exists

Set ʻexist_ok = True`

>>> Path('test/data').mkdir(exist_ok=True)

How to connect paths

Concatenate with / to the Path object You can do the same with / as ʻos.path.join ()`

>>> d = Path('data')
>>> d / 'train' / '001'
PosixPath('data/train/001')

Get parent directory

Use parent

>>> b
PosixPath('data/image_0001.jpg')
>>> b.parent
PosixPath('data')

At the end

This time I wrote it as my memorandum so that I don't forget the ones I use often. I hope it will be helpful as much as possible.

References

--Object-oriented file system path

-Get filename / extension / parent directory with Python, pathlib