How to use multiple versions of Python without uninstallation

Question

I am faced with a unique situation, slightly trivial but painful.

I need to use Python 2.6.6 because NLTK is not ported to Python 3 (that\'s what I could gather).

Answer 1

For those using windows, if you're not averse to using PowerShell, you can install python 2 and 3 separately as mentioned in other answers. Then you can do this:

Set-Alias python27 [some path]\python27\python.exe 
Set-Alias python33 [some path]\python33\python.exe

To create an alias for running each version.

Keeping aliases around is described in this link: https://msdn.microsoft.com/en-us/powershell/reference/5.1/microsoft.powershell.core/about/about_aliases#saving-aliases

In order to successfully load the profile that that link would have you create, you may need to change your execution policy.

Set-ExecutionPolicy RemoteSigned

should do the trick, but if you want to know more about execution policies you may want to follow this link: https://msdn.microsoft.com/en-us/powershell/reference/5.1/microsoft.powershell.core/about/about_execution_policies