I am using 18.04 Ubuntu with Anaconda.Recently i have trying to install OpenCV through conda-forge channel in the base environment. I did not install purposely any Python version and did not use any pip command either in base environment. Now, in the base environment, if execute just python, i get the same python version as system version and if execute python3 , i get the version installed by conda-forge. Please refer the screen shot. Python_on_Conda_base
I would like to know what is difference between python and python3 command?.What is should i keep in mind? basically i prefer the version 3.7.5 Python
.So, only the Python3 has uses different version. So, question what i should take note when i using python3 some_script.py? what is pros and cons of having this 2 version?
So far,i did not face any issues, but removed the conda-forge channel from Anaconda to avoid any conflicts. Any thoughts?
After posting this question, i have noticed python --version command gives Python 3.7.5 on Conda base environment and Ubuntu terminal (outside Conda)
You most likely have set an alias for python to point to the python3 binary.
Check this by typing type python, which will probably give you
python is aliased to ...
The crux here is that an alias will not be detected by which and as you revealed in the comments your which python returns the correct python version from your conda base environment, which makes an alias the most likely explanation, as PATH issues can be ruled out.
If above command does indeed reveal an alias, then check you .bashrc or similar file that you might have modified for a line alias python=.... Delete it, restart your terminal and everything should work normally
Related
I'm teaching myself python and have been exclusively been using Jupyter Notebooks through Anaconda until now. I'm now trying to move away from Jupyter and write .py scripts in an IDE. While working in Jupyter i've pip installed modules and they've worked fine within Jupyter. I've just discovered though that if i do this through an IDE i get a ModuleNotFoundError.
I've looked online and there are alot of posts with similar issues but none that quite matches mine. While i'm learning actual python code ok there is a huge hole in my knowledge around the setup, the terminal etc, and when i first started out i downloaded different IDE's which may not be helping...
Here's a few things from posts that i've tried that may give a clue as to what's wrong.
1) which python gives me //anaconda3/bin/python
2) which pip gives me //anaconda3/bin/pip
3) in python in the terminal:
import sys
for p in sys.path:
print(p)
//anaconda3/lib/python37.zip
//anaconda3/lib/python3.7
//anaconda3/lib/python3.7/lib-dynload
//anaconda3/lib/python3.7/site-packages
//anaconda3/lib/python3.7/site-packages/aeosa
4) usr/local/bin/ has a bunch of files (not folders) in it like 'Python3.7', 'Python3.7-config' etc
5) which -a pip = //anaconda3/bin/pip
6) which -a python gives me two paths = //anaconda3/bin/python
/usr/bin/python
7) usr/bin/python is a unix executable file, when i click it it opens a python terminal that says Python 2.7.16. within the usr/bin directory all the other python related files seem to reference 2.7.
8) when i pip install i generally just go 'pip install x' at the terminal. I thought maybe i needed to do 'pip3 install x' it would maybe not point just to anaconda, but was a complete guess and while the modules downloaded it didn't help at all.
9) I tried using an alias alias python=/usr/local/bin/python3 - but as python3 isn't actually there, i just created another problem that i then had to 'unalias'
10) pip -V = pip 19.1.1 from //anaconda3/lib/python3.7/site-packages/pip (python 3.7)
11) pip freeze showed the all the modules i would expect to see
This post seemed similar: Modules are installed using pip on OSX but not found when importing
Any help would be greatly, greatly appreciated. I've been learning ok up until now but i'm pretty out of my depth with this side of things, and i can't move forward at all unless i find a way to use an IDE with third party modules...
UPDATE - Tried uninstalling and reinstalling anaconda and it made no difference. All still works in Jupyter, modules can't be found elsewhere from IDEs. Also can't seem to install things like pandas through anaconda as it already has it, so it doesn't seem related to the IDE not being able to find it –
Thanks
When using the Anaconda distribution you should avoid pip as much as possible. Use the conda package manager instead. Try installing missing packages from the conda-forge channel first:
conda install newpackage -c conda-forge
Before you can use Anaconda properly, you need to activate it:
conda activate
The Jupyter start link did this for you. The Anaconda Prompt does the same thing and you can start your IDE directly from there. However, all IDE's manage environments themselfs, which is way more flexible. So it is time well spent to learn your IDE's features first.
On my Mac terminal i've installed python3 (3.7.6) using homebrew - e.g. if I issue command to upgrade via homebrew, it returns the up to date version:
$brew upgrade python3
Warning: python3 3.7.6_1 already installed
However when I ask for the version it tells me an older version (3.4.0) is installed:
$python3 --version
Python 3.4.0
So it's installed but not updated. I'd quite like 3.6 or later on my mac. I've tried uninstalling and reinstalling using homebrew, and had no luck. Wondering if anyone has any ideas?
//
Sidenote (1) - i'm relatively new to homebrew... $ brew doctor returns config scripts "outside your system or Homebrew directories" - not sure if this helps, and if this is the issue where to move them to.
/Library/Frameworks/Python.framework/Versions/3.4/bin/python3.4m-config
/Library/Frameworks/Python.framework/Versions/3.4/bin/python3-config
/Library/Frameworks/Python.framework/Versions/3.4/bin/python3.4-config
Sidenote (2) - 3.7.6 isn't the newest version out, but this is the latest version that homebrew will install. Is there any way to get an even newer version?
By chance i've come across the/a answer. I was editing .bash_profile and saw the very top says:
# Setting PATH for Python 3.4
# The orginal version is saved in .bash_profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/3.4/bin:${PATH}"
export PATH
So I moved to this directory .../Versions/, found it had three subdirectories 3.3, 3.4, and 3.8, and updated to use:
PATH="/Library/Frameworks/Python.framework/Versions/3.8/bin:${PATH}"
And this seems to do the trick (to use the most recent). Although interestingly i've not came across 3.7.6... but is a bit redundant in my case since I can use the newer 3.8 version.
Quick fix:
You should be able to run the required version by running python3.7 instead of python3. You can set up an alias if you like with
"alias python=/usr/local/bin/python3.7"
where you put the desired binary on the RHS. This will create an alias for your current session. To always evoke this functionality, you can add this line to your bashrc file so this alias will work every time you log in to a new session
echo "alias python=/usr/local/bin/python3.7" >> ~/.bashrc
These commands were lifted from
https://opensource.com/article/19/5/python-3-default-mac
which explains some do and do-nots.
Alternative:
Also check out Python virtual environments, particularly virtualenv and virtualenvwrapper, which are great tools for separating out your Python working environments and allow you to set default Python version for each project separately, as well as managing any modules you pip install separately for each project. This is much cleaner in my opinion.
https://www.bogotobogo.com/python/python_virtualenv_virtualenvwrapper.php
I'm trying to get wxPython to work in a pyenv-based virtualenv with the virtualenv and virtualenvwrapper plugins on MacOS. I've read several questions about making this work, but most of the answers seem to assume that I'm using the system python version, and/or only address one aspect of a broken setup. I haven't yet seen anything that explains what wxPython is checking for when it starts.
I have python 3.7 compiled by pyenv with --enable-framework.
env PYTHON_CONFIGURE_OPTS="--enable-framework" pyenv install 3.7.4
pyenv itself is installed in my homedir from a reasonably recent (within the last couple of weeks) pull from git.
To be clear, none of the tools or libraries in my Python toolchain are installed by Homebrew.
My virtualenv has access to the framework by virtue of --system-site-packages. Having access to the framework and to the display are supposedly all that's required for wxPython to work, yet I'm still getting the same error on start of any test app:
This program needs access to the screen. Please run with a
Framework build of python, and only when you are logged in
on the main display of your Mac.
It looks to me like everything I should need is available.
% pyenv which python3.7
/Users/matt/.pyenv/versions/3.7.4/bin/python3.7
% mkvirtualenv --system-site-packages --python python3.7 wxtest
Running virtualenv with interpreter /Users/matt/.pyenv/shims/python3.7
Already using interpreter /Users/matt/.pyenv/versions/3.7.4/Python.framework/Versions/3.7/bin/python3.7
Using base prefix '/Users/matt/.pyenv/versions/3.7.4/Python.framework/Versions/3.7'
New python executable in /Users/matt/.ve/wxtest/bin/python3.7
Also creating executable in /Users/matt/.ve/wxtest/bin/python
Installing setuptools, pip, wheel...
done.
virtualenvwrapper.user_scripts creating /Users/matt/.ve/wxtest/bin/predeactivate
virtualenvwrapper.user_scripts creating /Users/matt/.ve/wxtest/bin/postdeactivate
virtualenvwrapper.user_scripts creating /Users/matt/.ve/wxtest/bin/preactivate
virtualenvwrapper.user_scripts creating /Users/matt/.ve/wxtest/bin/postactivate
virtualenvwrapper.user_scripts creating /Users/matt/.ve/wxtest/bin/get_env_details
% python -m site
sys.path = [
'/Users/matt/devel/wxtest',
'/Users/matt/.ve/wxtest/lib/python37.zip',
'/Users/matt/.ve/wxtest/lib/python3.7',
'/Users/matt/.ve/wxtest/lib/python3.7/lib-dynload',
'/Users/matt/.pyenv/versions/3.7.4/Python.framework/Versions/3.7/lib/python3.7',
'/Users/matt/.ve/wxtest/lib/python3.7/site-packages',
'/Users/matt/.pyenv/versions/3.7.4/Python.framework/Versions/3.7/lib/python3.7/site-packages',
]
USER_BASE: '/Users/matt/.local' (exists)
USER_SITE: '/Users/matt/.local/lib/python3.7/site-packages' (doesn't exist)
ENABLE_USER_SITE: True
% pip install wxPython
Collecting wxPython
[...]
Successfully installed numpy-1.18.0 pillow-6.2.1 six-1.13.0 wxPython-4.0.7.post2
The code for IsDisplayAvailable() is buried in the _core shared object library, so not particularly easy to examine. I'm not a C++ coder, and digging around in the code repository all I've been able to find so far is the docstring in src/_app.i, not the actual code.
On Mac OS X a False return value will mean that wx is not
able to access the window manager, which can happen if logged in
remotely or if running from the normal version of python instead
of the framework version, (i.e., pythonw.)
That list of requirements seem to be satisfied by what I have here. I don't have a pythonw binary, but as the pythonw(1) man page says:
Actually, since Python 2.5, the normal python also allows GUI access, so
python and pythonw are now interchangeable.
Does anyone have an exhaustive list of what wxPython actually expects to find before it runs?
The error you're encountering is likely to be a "brew-hole" (a.k.a homebrew installation/compatibility issue for wxpython v3 and sometimes v4).
To test some issues that might be at hand perform the following in your pyenv:
python --version
python3 --version
How are they installed? Did you use brew?
If brew or any non-anaconda: uninstall all.
Then : reinstall python via the anaconda 2019. (xx >04) packaged version and it gives you 3.7.4 or 3.7.5 depending on what you choose.
reinstall via conda/pip cmd-line the required packages that are not with default install.
Anaconda "base" is your default environment.
Then conda create --name myenv where myenv is any name you give your environment. For example "myPythonwx408" environment.
cmdline: conda activate myenv
... and tada.. up you go...
If the error persist in anaconda env you can post the environment.yml file so I can recreate your environment for testing.
You mention "virtualenv". Is that the actual virtualenv package or just what you are calling the pyenv instance? If the former then try python -m venv instead. The virtualenv package still hides the framework-ness of the parent Python, even after all these years. The venv package is included with Python3 and is a much better/simpler implementation of the concept.
Here is what I get when I run the following commands in my terminal:
python --version
python 2.7.1
python3 --version
python 3.7.3
I ran the 'Update Shell Profile.command' file that comes with the Python3 download, but it still doesn't change the value of
python version
when I run it. My question is, is this normal? Does it change anything important other than needing to type 'python3 file.py' to run 'file.py'? If so, how do I change this? (Also, the computer I am using uses Homebrew which I am not familiar with, I am not sure if this changes anything or how.)
Python 2.7 and Python 3.7 are the latest releases of python 2 and 3 repsectively. Those two are two different version which can co-exist together. You can have both versions installed in your computer at the same time. If u dont like that just uninstall one(I'd suggest python2). The main difference is that python 3 offers many advantages compared to python 2. Some of them would be that some libraries work only for that version other legacy ones work for the other version etc. So there is no problem with having both but like i said there is really no point. Just choose whch version u like and uninstall the other one.
I use Pycharm to create and manage my virtualenvs in my projects.
The problem is that after adding a library with pycharm, when I type the command (pip3 freeze --user), the library does not appear in the command result.
I have to manually type the pip install command each time so that the library is visible.
What manipulation should I do in PyCharm to solve this problem?
For what you are saying, the first thing that comes to mind is that you should use:
pip freeze
And not
pip3 freeze
Because the command mapped to the pip version when you have virtualenv activated is the first. Note that for installing you seem to use pip, and not pip3
Moreover, the --user option afaik is related to the packages installed in the user folder:
--user Install to the Python user install directory for your platform. Typically
~/.local/, or %APPDATA%\Python on
Windows. (See the Python documentation for site.USER_BASE for full details.)
If your packages are installed in the virtualenv folder, I would tell you to not use that option.
Also please make sure you have your virtualenv activated. In linux you can do so by source path/to/virtualenv/activate
Edit
I understand that the reason you are using pip3 is because you may have different versions of Python in your machine. Let me explain you a bit further how it works, because version management is usually a headache for many programmers and it is common to find problems when doing so.
If you install different versions of Python in your linux machine, and you do that as root, then the installation will proceed for the whole system. Usually Python2 installation folder for Linux machines is /usr/bin/python. However, I am uncertain of which directory is used for Python3 installations. You can check that easily by doing whereis python3. You can serach the path to binary of any command by doing whereis command. Note that this works also for whereis python as far as you don't have virtualenv activated.
Aditionally, the link to the binary of a command (or the set of instructions to be exectued, more broadly) is defined in certain folders in Linux, depending on whether you created the command as root or as a user, and possibly also on the distro. This works differently in Windows, that uses the Registry Edit utility to handle command mappings. When you enable your virtualenv, what you are doing is creating an environment that enables mapping system commands such as python to the Python installation in your virtualenv folder.
When you disable the virtualenv, the command points again to the default installation path. Same happens with pip, so incorrect usage of this tool may result in different packages being installed in different locations, and therefore not appearing available for the right Python version at any given circumstance.
In Linux, environment variables are shell dependent, though you can write them out with echo $variable and set them with variable=value (from bash). The search path is simply called PATH and you can get yours by typing echo $PATH.
Source: https://askubuntu.com/a/262073/426469
I encourage you to check other questions in SE network such as this: https://unix.stackexchange.com/a/42211/96121, to learn more about this.
Addendum
Quick tip: it is common to use the pip freeze command as follows:
pip freeze > requirements.txt
It is a standard that leads to understanding that modules in such file are required for the correct functioning of your application. That lets you easily exclude the virtualenv folder when you install the program in another computer, since you can readily know the requriments for a fresh installation. However, you can use the command as you want.