Python Config

Install packages

Use which -a to see all python executables.

Conda Commands

https://docs.conda.io/projects/conda/en/stable/commands/init.html

conda init will add your conda executable file in your $PATH variable.

conda init [SHELLS] Available shells: [‘bash’, ‘fish’, ‘powershell’, ‘tcsh’, ‘xonsh’, ‘zsh’]. One or more shells to be initialized. If not given, the default value is ‘bash’ on unix and ‘cmd.exe’ & ‘powershell’ on Windows.

On Mac, when you install Anaconda or Miniconda, .bash_profile gets updated with the following code:

# >>> conda initialize >>>
# !! Contents within this block are managed by 'conda init' !!
__conda_setup="$('/Users/menghan/anaconda3/bin/conda' 'shell.bash' 'hook' 2> /dev/null)"
if [ $? -eq 0 ]; then
    eval "$__conda_setup"
else
    if [ -f "/Users/menghan/anaconda3/etc/profile.d/conda.sh" ]; then
        . "/Users/menghan/anaconda3/etc/profile.d/conda.sh"
    else
        export PATH="/Users/menghan/anaconda3/bin:$PATH"
    fi
fi
unset __conda_setup
# <<< conda initialize <<<

Issue: The result of default conda init is that the environment variable is inserted in .bash_profile even if zsh is your default shell.

Fix: You need to specify explicitly the shell to be zsh. Run conda init zsh will add the same code to .zshrc.

conda info display info about current conda install.

conda env list list all conda environments.

Determine your current env

By default, the active environment—the one you are currently using—is shown in parentheses () or brackets [] at the beginning of your command prompt:

(myenv) $

If you do not see this, run:

conda info --envs # list all envs, the active one is prefixed w/ *

In the environments list that displays, your current environment is highlighted with an asterisk (*).

To see if a specific package is installed in an environment:

conda list --name myenv scipy # full flag
conda list -n myenv scipy # same cmd but in shorthand
conda list scipy # check in the current-active env

conda list # print all installed packages
conda list -n myenv # print all installed packages in myenv

`conda install`

arguments:

-n, --name specify name of environment
-p, --prefix full path to environment location
-c, --channel Additional channel to search for packages.
a list of packages can be installed at once. Jist append pkgs together and separate by space.

Examples:

Install the package ‘scipy’ into the currently-active environment:
```
conda install scipy
```
Install a list of packages into an environment, myenv:
```
conda install -n myenv scipy curl wheel
```
Install a specific version of ‘python’ into an environment, myenv:
```
conda install -p path/to/myenv python=3.11
```

conda search Search packages in the default channel_alias https://conda.anaconda.org/. Can specify additional channel using conda search conda-forge::[some package name].

search for a specific package named ‘scikit-learn’:
```
conda search scikit-learn
```
Search for packages containing ‘scikit’ in the package name:
```
conda search *scikit* # [✘]
```
- Note that your shell may expand ‘*’ before handing the command over to conda. Therefore, it is sometimes necessary to use single or double quotes around the query:
```
conda search '*scikit' # [✔]
conda search "*scikit*" # [✔]
```
Search for a specific version of a package:
```
conda search 'numpy>=1.12'
```

Search for a package on a specific channel conda-forge:

conda search conda-forge::numpy
conda search 'numpy[channel=conda-forge, subdir=osx-64]'

Install packages from Anaconda.org

In a browser, go to http://anaconda.org.
To find the package named PyPortfolioOpt, type PyPortfolioOpt in the top-left box named Search Packages.
Follow the instructions in the detailed page.

Using `pip`

conda install -n myenv pip
conda activate myenv
pip <pip_subcommand>

Note: Issues may arise when using pip and conda together.

When combining conda and pip, it is best to use an isolated conda environment.
Only after conda has been used to install as many packages as possible, should pip be used to install any remaining software.

python -m pip executes pip using the Python interpreter you specified as python.

So /usr/bin/python3.7 -m pip means you are executing pip for your interpreter located at /usr/bin/python3.7.

python -m pip install SomePackage            # latest version, installed in the correct location for the python version you are using
python -m pip install SomePackage==1.0.4     # specific version
python -m pip install 'SomePackage>=1.0.4'     # minimum version

python -m module-name the given module is located on the Python module path and executed as a script.

Update Python

Using a different version of Python

conda activate myenv # activate myenv
conda update python # update Python to the latest version in the current env
conda install python=3.10 # update to a specific version of Python

Create a new environment for the new Python

conda create -n py39 python=3.9 # create a new env called py39
conda activate py39  # activate py39
python --version # print Python version

Viewing a list of available Python versions

To list the versions of Python that are available to install, in your terminal window, run:
```
conda search python # This lists all packages whose names contain the text `python`.
```
To list only the packages whose full name is exactly python, add the --full-name option.
```
conda search --full-name python
```

Install packages

conda install

Install packages from Anaconda.org

Using pip

Update Python

`conda install`

Using `pip`