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For a pure python module you can find the location of the source files by looking at the module.__file__. For example, >>> import mymodule >>> mymodule.__file__ C:/Users/Ayush/mymodule.py Many built in modules, however, are written in C, and therefore module.__file__ points to a .so file (there is no module.__file__ on Windows), and therefore, you can't see the source. You can manually go and check the PYTHONPATH variable contents to find the directories from where these built in modules are being imported. Running "python -v"from the command line tells you what is being imported and from where. This is useful if you want to ... Read More
json is simplejson, added to the stdlib. But since json was added in 2.6, simplejson has the advantage of working on more Python versions (2.4+).simplejson is also updated more frequently than Python. Although they are the same, the version included in the stdlib doesn't include the latest optimizations. So if you need (or want) the latest version, it's best to use simplejson itself, if possible.A good practice, is to use one or the other as a fallback. For example,try: import simplejson as json except ImportError: import json
The function reload(moduleName) reloads a previously loaded module (assuming you loaded it with the syntax "import moduleName". It is intended for conversational use, where you have edited the source file for a module and want to test it without leaving Python and starting it again. For example, >>> import mymodule >>> # Edited mymodule and want to reload it in this script >>> reload(mymodule)Note that the moduleName is the actual name of the module, not a string containing its name. In Python 3, reload was moved from builtins to imp. So to use reload in Python 3, you'd have to ... Read More
When you install Python, you also get the Python package manager, pip. You can use pip to get the versions of python modules. If you want to list all installed Python modules with their version numbers, use the following command:$ pip freezeYou will get the output:asn1crypto==0.22.0 astroid==1.5.2 attrs==16.3.0 Automat==0.5.0 backports.functools-lru-cache==1.3 cffi==1.10.0 ...To individually find the version number you can grep on this output on *NIX machines. For example:$ pip freeze | grep PyMySQL PyMySQL==0.7.11On windows, you can use findstr instead of grep. For example:PS C:\> pip freeze | findstr PyMySql PyMySQL==0.7.11If you want to know the version of a module ... Read More
The function reload(moduleName) reloads a previously loaded module (assuming you loaded it with the syntax "importmoduleName" without exiting the script. It is intended for conversational use, where you have edited the source file for a module and want to test it without leaving Python and starting it again. For example, >>> import mymodule >>> # Edited mymoduleand want to reload it in this script >>> reload(mymodule)Note that the moduleName is the actual name of the module, not a string containing its name. The python docs state following about reload function: Python modules’ code is recompiled and the module-level code re-executed, defining ... Read More
The "from module import function" statement is used to import a specific function from a Python module. For example, if you want to import the sin function from the math library without importing any other function, you can do it as follows:>>> from math import sin >>> sin(0) 0.0Note that you don't have to prefix sin with "math." as only sin has been imported and not math. Also you can alias imported functions. For example,>>> from math import cos as cosine >>> cosine(0) 1.0
The "from module import *" statement is used to import all function from a Python module. For example, if you want to import all functions from math module and do not want to prefix "math." while calling them, you can do it as follows:>>> from math import * >>> sin(0) 0.0 >>> cos(0) 1.0Note that for any reasonable large set of code, if you import * you will likely be cementing it into the module, unable to be removed. This is because it is difficult to determine what items used in the code are coming from 'module', making it easy ... Read More
To set the PYTHONPATH on Linux to point Python to look in other directories for the module and package imports, export the PYTHONPATH variable as follows:$ export PYTHONPATH=${PYTHONPATH}:${HOME}/fooIn this case, are adding the foo directory to the PYTHONPATH. Note that we are appending it and not replacing the PYTHONPATH's original value. In most cases, you shouldn't mess with PYTHONPATH. More often than not, you are doing it wrong and it will only bring you trouble.
To set the PYTHONPATH on Mac OS to point Python to look in other directories for module and package imports, export the PYTHONPATH variable as follows:$ export PYTHONPATH=${PYTHONPATH}:${HOME}/foo In this case are adding the foo directory to the PYTHONPATH. Note that we are appending it and not replacing the PYTHONPATH's original value. In most cases, you shouldn't mess with PYTHONPATH. More often than not, you are doing it wrong and it will only bring you trouble
To set the PYTHONPATH on windows to point Python to look in other directories for module and package imports, go to:My Computer > Properties > Advanced System Settings > Environment VariablesThen under system variables edit the PythonPath variable. At the end of the current PYTHONPATH, add a semicolon and then the directory you want to add to this path:C:\Python27;C:\fooIn this case, are adding the foo directory to the PYTHONPATH. Note that we are appending it and not replacing the PYTHONPATH's original value. In most cases, you shouldn't mess with PYTHONPATH. More often than not, you are doing it wrong and ... Read More