Python Programming/Files

From Wikibooks, the open-content textbooks collection

Jump to: navigation, search

← Modules and how to use them| Text →

[edit] File I/O

Read entire file:

inputFileText = open("testit.txt", "r").read()
print inputFileText

Read certain amount of bytes from a file:

inputFileText = open("testit.txt", "r").read(123)
print inputFileText

Read one line at a time:

for line in open("testit.txt", "r").readlines():
    print line

Write to a file:

outputFileText = "Here's some text to save in a file"
open("testit.txt", "w").write(outputFileText)

Append to a file:

outputFileText = "Here's some text to add to the existing file."
open("testit.txt", "a").write(outputFileText)

Note that this does not add a line break between the existing file content and the string to be added.

[edit] Testing Files

Determine whether path exists:

import os
os.path.exists('<path string>')

When working on systems such as Microsoft Windows(tm), the directory separators will conflict with the path string. To get around this, do the following:

import os
os.path.exists('C:\\windows\\example\\path')

A better way however is to use "raw", or r:

import os
os.path.exists(r'C:\windows\example\path')

[edit] Common File Operations

To copy or move a file, use the shutil library.

import shutil
shutil.move("originallocation.txt","newlocation.txt")
shutil.copy("original.txt","copy.txt")
Previous: Modules and how to use them Index Next: Text
Personal tools