File Stuff

import glob

glob.glob("/usr/local/*) -- return a list of actual file path

os.listdir()

Code segment to iterate a folder using a callback:

import os

import sys

def func_walker(arg, dirName, itemNames):

    for oneItemName in itemNames:

        onePath = os.path.join(dirName, oneItemName)

        if os.path.isdir(onePath):

            print "\t%s/" % oneItemName

        else:

            print "\t%s" % oneItemName

    print

for one_arg in sys.argv[1:]:

    file_path = os.path.abspath(one_arg)

    os.path.walk(file_path, func_walker, None);

Code segment to iterate a folder using a for loop:

import os

import sys

for one_arg in sys.argv[1:]:

    file_path = os.path.abspath(one_arg)

    for thisDir, subDirs, filesHere in os.walk(file_path):

        print "thisDir = ", thisDir

        print "subDirs = ", subDirs

        print "filesHere = ", filesHere

We can retrieve the file path for the script that started the process:

cur_path = sys.path[0]

if (len(cur_path) > 0):

...

The check is needed 'cos it may be an empty string.

To check if a file path is real or not:

os.path.exists(file_path)

Empty a folder content:

     import shutil

     shutil.rmtree('/path/to/folder')

Create folder(s) following the path

     os.makedirs('path/to/new_folder')

Split file name and extension:

theName, theExt = os.path.splitext(oneFile)

theExt will start with '.' or empty string

To output the dir that contains the current running script:

import os

script_dir = os.path.dirname(os.path.realpath(__file__)) + os.sep

Read file line by line:

theList = [];

rfile = open("test-line.txt")

while 1:

    line = rfile.readline()

    if (line == None) or (0 >= len(line)):

        break

    # line = line.strip()

    print '"' + line + '"'

    theList.append(line)

In newer Python, we can do the following:

theFile = open("../readme.txt")

for oneLine in theFile:

    print oneLine,

with open(full_path) as the_file:

    for one_line in the_file:

        ...

Read a CSV file:

import sys

import csv

csv.field_size_limit(sys.maxsize)

# rfile = csv.reader(open(target_file_name, 'rb'))
rfile = csv.reader(open(target_file_name, 'r'))

for row in rfile:

    print row[0]

or

rfile = csv.DictReader(open(target_file_name, 'rU'))

print rfile.fieldnames  # the first row normally

for row in rfile:

    print row[rfile.fieldnames[0]] # first field name, may not be the first one in the list

Write a list to CSV file:

import csv

wfile = open(r'test-line.csv','wb')

w = csv.writer(wfile, dialect='excel', quoting=csv.QUOTE_ALL)

w.writerow(theList)

Or

data1 = { 'apple': 1, 'banana': 2, 'orange': 3, }

data2 = {'apple': 11, 'banana': 21, 'orange': 31, }

field_order2 = ['apple', 'banana', 'orange']

csv_writer = csv.DictWriter(open('test-20130610.csv', 'wb'), fieldnames = field_order2, dialect='excel')

csv_writer.writeheader()

csv_writer.writerow(data1)

csv_writer.writerow(data2)

Image Header:

import imghdr

imageType = imghdr.what(srcFullPath)

Copy File

import shutil

shutil.copy2(srcFullPath, finalDstPath)

Zip File

import zipfile

zipper = zipfile.ZipFile(zipFilePath, 'w')

for thisDir, subDirs, filesHere in os.walk(absPath):

    for oneFile in filesHere:

        # this will create a flat file structure

        # take out second param ('oneFile') will create a hierarchical structure from the path in the first parameter 

        zipper.write(os.path.join(thisDir, oneFile), oneFile)

Read File

theFile = open(file_path, 'rb')

buf = theFile.read()

if (buf != None):

    ...

theFile.close()

Write File

theFile = open(thePath, 'wb')

strToFile = ...

theFile.write(strToFile)

theFile.close()

Links:

A python replacement for java.util.Properties (Python recipe)