Hey everyone I installed Python3.9 on my Mac using homebrew package manager but now I do not know how to install packages to it for use
Can anyone please tell me, thanks !
You should first do some research on the Python virtual environment, but the final answer to your question is to use pip install for installing Python packages. Be aware that there are other options out there, but pip is the most prevalent.
When you installed python, it has pip installed by default. pip comes with python. You can check pip version by
pip --version
OR
pip3 --version
Now, in order to install any other package, you can install by
pip install <package-name>
It would be better if you install a virtual environment, and install all other packages inside the virtual environment so that you can install packages according to your project requirements and with different versions.
To install virtual environment, do
pip install virtualenv
Once the virtual environment is installed, you can create your virtualenv according to your project requirement by:
virtualenv -p python3 venv
Here venv is your virtualenv name. To activate it,
source venv/bin/actiavte
Now, you can install all your required packages inside this virtualenv by pip3 install <package-name>. This will keep it separated from your system environment.
Related
I have been advised using pip in a Anaconda virtual environment is bad. But some packages are not on conda or on conda forge.
When I run
conda activate virtualenv
where pip
I get two paths, one which is outside the environment
C:\Anaconda\virtualenv\Scripts\pip.exe
C:\Anaconda\Scripts\pip.exe
How do I fix it, so that when I do pip install package it only installs in the virtual environment?
The command line should use the first pip it finds, which in your case is the one in the virtual environment. This pip will only install packages in your environment. You can check which one is running with pip --version.
I'm using Linux Mint 20.2 with two directories / and /home.
I used the following command to install virtualenv:
>>> sudo pip3 install virtualenv
It worked fine and it installed in the following path:
>>> virtualenv --version
virtualenv 20.0.17 from /usr/lib/python3/dist-packages/virtualenv/__init__.py
But when I tried to create an environment I got the following error:
>>> python3 -m venv article
The virtual environment was not created successfully because ensurepip is not
available. On Debian/Ubuntu systems, you need to install the python3-venv
package using the following command.
apt install python3.8-venv
You may need to use sudo with that command. After installing the python3-venv
package, recreate your virtual environment.
Failing command: ['/home/username/article_tools/article/bin/python3', '-Im', 'ensurepip', '--upgrade', '--default-pip']
When I tried to uninstall it to install it using [b]sudo apt install python3.8-venv[/b], I got the following error:
>>> sudo pip3 uninstall virtualenv
Found existing installation: virtualenv 20.0.17
Not uninstalling virtualenv at /usr/lib/python3/dist-packages, outside environment /usr
Can't uninstall 'virtualenv'. No files were found to uninstall.
How can I fix it? By fix, I mean installing virtualenv in a way that I don't get such errors.
The fundamental problem here seems to be that you are mixing up two different packages.
Python 3 comes with a built-in virtual environment module venv which is however not installed by default on Debian-based platforms. Like the error message says, apt-get install -y python3-venv will install this package, which you can then use with python3 -m venv.
virtualenv is a separate third-party package which you invoke with the command virtualenv. It's not a bad alternative, but if you are only just learning, I would suggest you simply ignore it for the time being.
I used pyenv, pyenv-virtualenv for managing python virtual environment.
I have a project working in Python 3.4 virtual environment.
So all installed packages(pandas, numpy etc) are not newest version.
What I want to do is to upgrade Python version from 3.4 to 3.6 as well as upgrade other package version to higher one.
How can I do this easily?
Here is how you can switch to 3.9.0 for a given virtual environement venv-name:
pip freeze > requirements-lock.txt
pyenv virtualenv-delete venv-name
pyenv virtualenv 3.9.0 venv-name
pip install -r requirements-lock.txt
Once everything works correctly you can safely remove the temporary requirements lock file:
rm requirements-lock.txt
Note that using pip freeze > requirements.txt is usually not a good idea as this file is often used to handle your package requirements (not necessarily pip freeze output). It's better to use a different (temporary) file just to be sure.
Use pip freeze > requirements.txt to save a list of installed packages.
Create a new venv with python 3.6.
Install saved packages with pip install -r requirements.txt. When pip founds an universal wheel in its cache it installs the package from the cache. Other packages will be downloaded, cached, built and installed.
OP asked to upgrade the packages alongside Python. No other answers address the upgrade of packages. Lock files are not the answer here.
Save your packages to a requirements file without the version.
pip freeze | cut -d"=" -f1 > requirements-to-upgrade.txt
Delete your environment, create a new one with the upgraded Python version, then install the requirements file.
pyenv virtualenv-delete venv-name
pyenv virtualenv 3.6.8 venv-name
pip install -r requirements-to-upgrade.txt
The dependency resolver in pip should try to find the latest package. This assumes you have the upgrade Python version installed (e.g., pyenv install 3.6.8).
If you use anaconda, just type
conda install python==$pythonversion$
Python2.6 was installed by default in my old centos server. Now I want to create a Python3 environment to install python3 specific module by conda
conda create -n py3 python=3.5.3
source activate py3
After activate the py3, I try to install hovercraft by pip3 install hovercraft, the shell tells "command not found: pip3". At first I thought pip3 was installed with Python3, but the result was not the case.
So I think I can install it manually. The package gzip file was downloaded from python package index, and install by conda install --file hovercraft-2.3.tar.gz. But it doesn't work.
Now I have two problems:
how to install pip3 for virtual-env create by conda?
Is it possible to install python package index downloaded package locally in conda?
pip3 and pip would make a difference only when you are not using any environment managers like virualenv (or) conda. Now as you are creating a conda environment which has python==3.x, pip would be equivalent to pip3.
I use python's pip to install packages. Now I want to install scipy, which is already installed on the system, but an old version and on a part of the system where I don't have access to. If I try
pip install scipy
pip rightfully tells me that the package is already installed. If I do
pip install scipy --upgrade
pip tries to upgrade the package but I don't have the access rights to do that.
How can I tell pip to install the package local to my user and to ignore the other scipy package?
I think the best way for avoid override packages it's using a virtual environment. Python has it's own virtual environment and you could install it by:
Python 2.7
> sudo apt-get install python-virtualenv
Python 3
> sudo apt-get install virtualenv
With modern python versions, virtualenv is usually included. Once installed, you could generate a virtual enviroment typing:
> virtualenv venv
This would create a folder in the current directory named venv (you could name it whatever you want). In this package the libraries will be installed.
So, it's time to activate the virtual environment
> source venv/bin/activate
You could verify the environment has been activated by checking the prompt changes. If it happens, all the packages installed using pip will be installed locally.
(venv)> pip install scipy
You could check this website for more info.
Don't forget that you eventually have to clear your $PYTHONPATH variable, in order for it to not pick up other packages.