Tutorial on System Functions

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Bikash Santra

Indian Statistical Institute, Kolkata

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1. Import

import os 
import shutil

2. Knowing present working directory

# Knowing present working directory
xx = os.getcwd()
print(xx)

D:\Python ISI Chennai Teaching\1_PGDSMA

3. Listing files and folders present in the directory

# Knowing files and folders present in the directory

yy = os.listdir(xx)
# print(yy)

for file_folder in yy:
    print(file_folder)

.ipynb_checkpoints
1_Introduction.html
1_Introduction.ipynb
2_PythonBasics_I.html
2_PythonBasics_I.ipynb
3_PythonBasics_II.html
3_PythonBasics_II.ipynb
4_Numpy.html
4_Numpy.ipynb
5_Matplotlib.ipynb
6_Pandas.html
6_Pandas.ipynb
7_SystemFunctions.ipynb
8_Scipy.ipynb
afile
brics_test.csv
brics_test.xlsx
brisks_test.csv
horizontal.png
indexPagePGDSMA.ipynb
matplotlib-logo.png
numpy-logo.jpg
N_brics.xlsx
pythonLogo.png
Pytorch_logo.png
scikit-learn.png

4. Change the present working directory

# Change the directory

path = "D:\Python ISI Chennai Teaching"

os.chdir(path)
print(os.getcwd())

D:\Python ISI Chennai Teaching

os.chdir(xx)
print(os.getcwd())

D:\Python ISI Chennai Teaching\1_PGDSMA

5. Creating new directory

# Creating new directory

dirName = xx + '/test'

# Checking existance of folder
if not os.path.isdir(dirName):
    os.mkdir(dirName)
    
print(dirName)

D:\Python ISI Chennai Teaching\1_PGDSMA/test

6. Creating nested (or chain of) directories

# Creating chain of directories 

dirName_new = dirName + '/test_1/test_2/test_3/test_4/'

os.makedirs(dirName_new)

7. Checking the existance of a file

# Checking existance of file

fileName = xx + '/afile'

if os.path.isfile(fileName):
    print(fileName)

D:\Python ISI Chennai Teaching\1_PGDSMA/afile

8. Copying the files/folders

# Copying of file/folder

sourceFile = fileName
destFile = dirName + '/test_1/test_2/test_3/afile'

shutil.copy(sourceFile, destFile)

# Copy and rename

sourceFile = dirName + '/test_1/test_2/test_3/afile'
destFile = dirName + '/test_1/a_1_file'

shutil.copy(sourceFile, destFile)

'D:\\Python ISI Chennai Teaching\\1_PGDSMA/test/test_1/a_1_file'

9. Moving the files/folders

# Moving of file/folder

sourceFile = dirName + '/test_1/a_1_file'
destFile = dirName + '/test_1/test_2/a_1_file'

shutil.move(sourceFile, destFile)

'D:\\Python ISI Chennai Teaching\\1_PGDSMA/test/test_1/test_2/a_1_file'

10. Renaming file/folder

# Renaming file
oldName = xx + '/' + 'N_brics.xlsx'
newName = xx + '/' + 'brics.xlsx'

os.rename(oldName,newName)

# Renaming folder

old = 'D:/Python ISI Chennai Teaching/1_PGDSMA/test/test_1/test_2'
new = 'D:/Python ISI Chennai Teaching/1_PGDSMA/test/test_1/test_X'

os.rename(old,new)

old = 'D:/Python ISI Chennai Teaching/1_PGDSMA/test/test_1/test_X'
new = 'D:/Python ISI Chennai Teaching/1_PGDSMA/test/test_1/test_2'

os.rename(old,new)

11. Removing/deleting the directories

# Removing/deleting the empty directory
print(dirName_new)

os.rmdir(dirName_new)

D:\Python ISI Chennai Teaching\1_PGDSMA/test/test_1/test_2/test_3/test_4/

print(os.listdir(dirName_new[:-8]))

['afile']

os.removedirs(dirName_new[:-8])

---------------------------------------------------------------------------
OSError                                   Traceback (most recent call last)
<ipython-input-21-d9d7b710160b> in <module>
----> 1 os.removedirs(dirName_new[:-8])

C:\ProgramData\Anaconda3\lib\os.py in removedirs(name)
    239 
    240     """
--> 241     rmdir(name)
    242     head, tail = path.split(name)
    243     if not tail:

OSError: [WinError 145] The directory is not empty: 'D:\\Python ISI Chennai Teaching\\1_PGDSMA/test/test_1/test_2/test_3'

# Delete folder with its contents

shutil.rmtree(dirName_new[:-8])