Input/Output Files#

Files and Directories#

How to write a path string in Python:

path = "C:\\myfolder\\temp"     # escaped backslashes
path = "C:/myfolder/temp"       # forward slashes (cross-platform)
path = r"C:\myfolder\temp"      # raw string (recommended on Windows)

A string prefixed with r or R is a raw string — backslashes are treated as literal characters.

Module os#

The os module provides functions for file and directory operations.

Function	Description
`os.chdir(path)`	Change the current working directory
`os.listdir(path)`	List entries in a directory
`os.makedirs(path)`	Create a directory (including intermediate ones)
`os.remove(file)`	Delete a file
`os.rmdir(path)`	Delete an empty directory
`os.rename(old, new)`	Rename a file or directory
`os.path.exists(path)`	Return True if path exists
`os.walk(path, topdown=True)`	Walk a directory tree, yielding `(dirpath, dirnames, filenames)`

# Delete everything inside a directory (use with caution!)
import os

for root, dirs, files in os.walk(r"E:\myfolder", topdown=False):
    for name in files:
        os.remove(os.path.join(root, name))
    for name in dirs:
        os.rmdir(os.path.join(root, name))

# Create a directory if it doesn't exist
import os

mydir = r"D:\temp"
if not os.path.exists(mydir):
    os.makedirs(mydir)

# Delete an empty directory
import os

mydir = r"D:\temp"
if os.listdir(mydir) == []:
    os.rmdir(mydir)

Module shutil#

The shutil module provides high-level file and directory operations.

Function	Description
`shutil.move(src, dst)`	Move a file or directory
`shutil.copy(src, dst)`	Copy a file (preserving permissions)
`shutil.copytree(src, dst)`	Copy an entire directory tree
`shutil.rmtree(path)`	Delete a directory tree recursively

# Move all files from one directory to another
import shutil
import os
import glob

mydir = r"D:\workdir"
tempdir = r"D:\workdir\temp"
if not os.path.exists(tempdir):
    os.makedirs(tempdir)

filelist = glob.glob(os.path.join(mydir, "*"))
for file in filelist:
    shutil.move(file, tempdir)

Module zipfile#

The zipfile module provides tools to create, read, write, and extract ZIP archives.

Method	Description
`ZipFile(path, mode)`	Open or create a ZIP archive (`"w"` write, `"r"` read, `"a"` append)
`zf.write(file, arcname, compress_type)`	Add a file to the archive
`zf.extractall(path)`	Extract all files to a directory

import glob
import zipfile

mydir = r"D:\workdir"

with zipfile.ZipFile(os.path.join(mydir, "zippedfiles.zip"), "w") as zipped:
    for f in glob.glob(os.path.join(mydir, "*.pdf")):
        zipped.write(f, os.path.basename(f), compress_type=zipfile.ZIP_DEFLATED)

Note

Always use with statements to ensure files are properly closed.

Module glob#

The glob module finds pathnames matching a shell-style pattern.

Pattern	Meaning
`?`	Matches any single character
`*`	Matches zero or more characters
`[seq]`	Matches any character in seq (`-` for range)

>>> import glob
>>> glob.glob(r'C:\temp\card?.gif')
['C:\\temp\\card1.gif', 'C:\\temp\\card2.gif']
>>> glob.glob(r'C:\temp\*.gif')
['C:\\temp\\1g.gif', 'C:\\temp\\card1.gif', 'C:\\temp\\card2.gif']
>>> glob.glob(r'C:\temp\[0-9]*')
['C:\\temp\\1g.gif', 'C:\\temp\\2a.txt']

Running a Python File#

# From another script (Python 3)
exec(open("C:/Temp/Test.py").read())

# From the command line
$ python C:/Temp/Test.py

Warning

execfile() was removed in Python 3. Use exec(open(...).read()) or better yet, import the script as a module.

Reading Keyboard Input#

>>> name = input("Enter your name: ")
Enter your name: Alice
>>> name
'Alice'

Note

In Python 3, input() always returns a string. Use int(input(...)) or float(input(...)) to read numbers. The raw_input() function from Python 2 was removed — input() in Python 3 behaves like Python 2’s raw_input().