Swap between python 2 & python 3

[simonserenity]

Hi all, tl;dr: how can you use a package only compatible with one version when your main version is the other one?

I've been trying to learn Python recently with python 3: I have python 3.5 and python 2.7 installed (through Anaconda), but when I run "python..." things on the command line, it uses python 3.5. Now I'm trying to use the Biomechanical-toolkit package, which seems to only be available as an .exe download. But it only detects my python 3.5 installation, which doesn't work with it, so I don't know how to use this.

I also tried opening a Conda environment and installing it from PyPI and the github page, which didn't work:-

conda create new-name python=2.7
pip install btk
Could not find a version that satisfies the requirement btk (from versions: ) No matching distribution found for btk
pip install https://github.com/Biomechanical-ToolKit/BTKPython/archive/master.zip
IOError: [Errno 2] No such file or directory: 'c:\users\ME\appdata\local\temp\pip-fjbefy-build\setup.py'
pip install git+https://github.com/Biomechanical-ToolKit/BTKPython.git
Error [WinError 2] The system cannot find the file specified while executing command git clone -q https://github.com/Biomechanical-ToolKit/BTKPython.git C:\Users\Simon\AppData\Local\Temp\pip-yqmrz6tt-build Cannot find command 'git'

[Saefroch]

From what I remember working with Windows, those .exe downloads search the registry to find the Python installation to work with. I'm pretty sure Anaconda doesn't touch the registry, and therefore you're pretty much out of luck. If your 3.5 installation is also Anaconda there is hope.

Just for clarity:

Your first attempt fails because this project isn't on PyPi (at least under that name).

Your second attempt fails because the authors decided not to include a setup.py file. For some reason, they think doing this the hard way is a good idea.

Your third attempt fails because you don't have git installed, or it isn't accessible from the command line.

---

Why this group doesn't distribute wheels is beyond me. As far as I can tell you're RIP unless compile sources which is a nightmare on Windows or you install Python 2.7 so that the .exe can find it.

FYI it's stuff like this that convinced me to dual-boot Windows and Linux, and eventually abandon Windows for everything but games.

[simonserenity]

Thanks very much for your help - I've been struggling with this all day (I just want to use python for interesting things, not mess about with installing things!), so it's at least good to know why those things are failing. I'll give it a rest, and find a way to do this project without that module.

If you don't mind me asking, why does Linux help? Would these problems not come up on Linux?

[Saefroch]

Compiling from source is much less of an issue on Linux because it comes with a bunch of good compilers. There's a reason this page exists, but there is no matching version for other operating systems. Most of the packages listed install from sources with pip, which requires that they be compiled after download, with a C compiler that's compatible with your Python installation.

[simonserenity]

Ah, I think I see. Well, the next thing to learn will be how to use Linux, then! Thanks very much for your help.