Managing the file system¶

Old style¶

All the common operations are built into Python Static or classless os.path

Python 3.6 or higher¶

Class based Path from pathlib library

Better performance as it can avoid calls to the OS

Working with paths¶

# Python 3.6 or higher
# Grab the library
from pathlib import Path

# Where am I?
cwd = Path.cwd()
print(str(cwd))

# Combine parts to create full path and file name
new_file = Path.joinpath(cwd, 'new_file.txt')
print(str(new_file))

# Does this exist?
print(str(new_file.exists))

Working with directories¶

from pathlib import Path
cwd = Path.cwd()

# Get the parent directory
parent = cwd.parent

# Is this a directory
print(str(parent.is_dir())) # True

# Is this a file?
print(str(parent.is_file())) # False

# List child directories
for child in parent.iterdir():
    if child.is_dir():
        print(str(child)) # 打印当前目录的子文件夹

Working with files¶

from pathlib import Path
cwd = Path.cwd()
demo_file = Path(Path.joinpath(cwd, 'demo.txt'))

# Get the file name
print(str(demo_file.name))

# Get the extension
print(str(demo_file.suffix))

# Get the folder
print(str(demo_file.parent.name))

# Get the size
print(str(demo_file.stat().st_size))

Opening a file¶

stream = open(file_name, mode, buffer_size)

Mode:

r - Read(default)
w - Truncate and write
a - Append if file exists
x - Write, fail if file exists
+ - Updating (read/write)
t - Text(default)
b - Binary

Reading from a file¶

stream = open('demo.txt')

print(stream.readable()) # Can we read?
print(stream.read(1)) # Read the first character
print(stream.readline()) # Read a line

stream.close() # close the stream

Write to a file¶

stream = open('output.txt', 'wt') # write text

stream.write('H') # write a single string
stream.writelines(['ello', ',', 'world']) # write multiple strings
stream.write('\n') # Write a new line

stream.close() # close the stream (and flush data)

Managing the stream¶

stream = open('output.txt', 'wt')
stream.write('demo!')
stream.seek(0) # Put the cursor back at the start
stream.write('cool')
stream.flush() # Write the data to file
stream.close() # Flush and close the stream