Python Browsing Directories Copyright Software Carpentry and The

Python Browsing Directories Copyright © Software Carpentry and The University of Edinburgh 2010 -2011 This work is licensed under the Creative Commons Attribution License See http: //software-carpentry. org/license. html for more information.

We can use Python to Python Browsing Directories

We can use Python to – Save data to files Python Browsing Directories

We can use Python to – Save data to files – Read data from files Python Browsing Directories

We can use Python to – Save data to files – Read data from files But we might also want to Python Browsing Directories

We can use Python to – Save data to files – Read data from files But we might also want to – See what files we have Python Browsing Directories

We can use Python to – Save data to files – Read data from files But we might also want to – See what files we have – Delete files Python Browsing Directories

We can use Python to – Save data to files – Read data from files But we might also want to – See what files we have – Delete files – Group these into directories Python Browsing Directories

We can use Python to – Save data to files – Read data from files But we might also want to – See what files we have – Delete files – Group these into directories – Structure these directories into a tree Python Browsing Directories

We could use the shell Python Browsing Directories

We could use the shell Our program will be a mixture of – Python Browsing Directories

We could use the shell Our program will be a mixture of – Python – Shell commands Python Browsing Directories

We could use the shell Our program will be a mixture of – Python – Shell commands This is not portable Python Browsing Directories

We could use the shell Our program will be a mixture of – Python – Shell commands This is not portable Do it all in Python Browsing Directories

>>> from os import getcwd Python Import getcwd from the os module Browsing Directories

>>> from os import getcwd >>> getcwd() Python Browsing Directories

>>> from os import getcwd >>> getcwd() '/users/vlad' Python Current working directory Browsing Directories

>>> from os import getcwd >>> getcwd() '/users/vlad' >>> originaldir = getcwd() Python Save the current working directory in a variable Browsing Directories

>>> from os import getcwd >>> getcwd() '/users/vlad' >>> originaldir = getcwd() >>> print originaldir Python Use the variable Browsing Directories

>>> from os import getcwd >>> getcwd() '/users/vlad' >>> originaldir = getcwd() >>> print originaldir /users/vlad Python Browsing Directories

>>> from os import listdir Python Browsing Directories

>>> from os import listdir >>> listdir('. ') vlad bin data pizza. cfg Python mail music notes. txt solar. pdf swc papers Browsing Directories

>>> from os import listdir >>> listdir('. ') Current working directory vlad bin data pizza. cfg Python mail music notes. txt solar. pdf swc papers Browsing Directories

>>> from os import listdir >>> listdir('. ') ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] vlad bin data pizza. cfg Python mail music notes. txt solar. pdf swc papers Browsing Directories

>>> from os import listdir >>> listdir('. ') ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] vlad bin data pizza. cfg Python mail music notes. txt solar. pdf swc papers Browsing Directories

>>> listdir('. ') Python Browsing Directories

>>> listdir(getcwd()) Python Use the result of getcwd as the input directory to listdir Browsing Directories

>>> listdir(getcwd()) ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] Python Browsing Directories

>>> listdir(originaldir) Python Use a variable as the input directory to listdir Browsing Directories

Use a variable as the >>> listdir(originaldir) input directory to listdir ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] Python Browsing Directories

>>> listdir(originaldir) ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] >>> files = listdir(originaldir) Python Browsing Directories

>>> listdir(originaldir) ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] >>> files = listdir(originaldir) >>> print files Python Browsing Directories

>>> listdir(originaldir) ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] >>> files = listdir(originaldir) >>> print files ['solar', 'mail', 'pizza. cfg', 'notes. txt', 'swc', 'data', 'papers', 'solar. pdf', 'bin', 'music'] Python Browsing Directories

>>> for file in files: Python Remember the colon Browsing Directories

>>> for file in files: . . . print file Remember the 4 spaces Python Browsing Directories

>>> for file in files: . . . print file. . . Remember RETURN to close the loop Python Browsing Directories

>>> for file in files: . . . print file. . . solar mail pizza. cfg notes. txt swc data papers solar. pdf bin music Python bin data pizza. cfg vlad mail music notes. txt solar. pdf swc papers Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir Python Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') Python Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') >>> getcwd() Python Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') >>> getcwd() '/users/vlad/data' Python chdir changes the current working directory Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') >>> getcwd() '/users/vlad/data' >>> listdir(getcwd()) Python Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') >>> getcwd() '/users/vlad/data' >>> listdir(getcwd()) ['morse. txt', 'pdb', 'planets. txt', 'amino_acids. txt', 'elements', 'sunspot. txt'] Python Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') >>> getcwd() '/users/vlad/data' >>> listdir(getcwd()) ['morse. txt', 'pdb', 'planets. txt', 'amino_acids. txt', 'elements', 'sunspot. txt'] >>> chdir(originaldir) Python Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') >>> getcwd() '/users/vlad/data' >>> listdir(getcwd()) ['morse. txt', 'pdb', 'planets. txt', 'amino_acids. txt', 'elements', 'sunspot. txt'] >>> chdir(originaldir) >>> getcwd() Python Browsing Directories

>>> getcwd() '/users/vlad' >>> from os import chdir >>> chdir('data') >>> getcwd() '/users/vlad/data' >>> listdir(getcwd()) ['morse. txt', 'pdb', 'planets. txt', 'amino_acids. txt', 'elements', 'sunspot. txt'] >>> chdir(originaldir) >>> getcwd() '/users/vlad' Python Browsing Directories

>>> chdir('data') root / bin data users tmp imhotep larry vlad data Python Browsing Directories

>>> chdir('data') >>> getcwd() root / bin data users tmp imhotep larry vlad data Python Browsing Directories

>>> chdir('data') >>> getcwd() '/users/vlad/data' root / bin What Python considers to be the current working directory Python data users tmp imhotep larry vlad data Browsing Directories

>>> chdir('data') >>> getcwd() '/users/vlad/data' >>> CTRL-D root / bin What Python considers to be the current working directory Python data users tmp imhotep larry vlad data Browsing Directories

>>> chdir('data') >>> getcwd() '/users/vlad/data' >>> CTRL-D $ pwd What Python considers to be the current working directory Python root / bin data users tmp imhotep larry vlad data Browsing Directories

>>> chdir('data') >>> getcwd() '/users/vlad/data' >>> CTRL-D $ pwd '/users/vlad' What the shell considers to be the current working directory What Python considers to be the current working directory Python root / bin data users tmp imhotep larry vlad data Browsing Directories

os Miscellaneous operating system interfaces getcwd Get current working directory listdir List directory contents chdir Change directory Python Browsing Directories

created by Mike Jackson and Greg Wilson May 2011 Copyright © Software Carpentry and The University of Edinburgh 2010 -2011 This work is licensed under the Creative Commons Attribution License See http: //software-carpentry. org/license. html for more information.