Using conda install within a python script

You can use conda.cli.main. For example, this installs numpy:

import conda.cli

conda.cli.main('conda', 'install',  '-y', 'numpy')

Use the -y argument to avoid interactive questions:

-y, --yes Do not ask for confirmation.

Having worked with conda from Python scripts for a while now, I think calling conda with the subprocess module works the best overall. In Python 3.7+, you could do something like this:

import json
from subprocess import run


def conda_list(environment):
    proc = run(["conda", "list", "--json", "--name", environment],
               text=True, capture_output=True)
    return json.loads(proc.stdout)


def conda_install(environment, *package):
    proc = run(["conda", "install", "--quiet", "--name", environment] + packages,
               text=True, capture_output=True)
    return json.loads(proc.stdout)

As I pointed out in a comment, conda.cli.main() was not intended for external use. It parses sys.argv directly, so if you try to use it in your own script with your own command line arguments, they will get fed to conda.cli.main() as well.

@YenForYang's answer suggesting conda.cli.python_api is better because this is a publicly documented API for calling conda commands. However, I have found that it still has rough edges. conda builds up internal state as it executes a command (e.g. caches). The way conda is usually used and usually tested is as a command line program. In that case, this internal state is discarded at the end of the conda command. With conda.cli.python_api, you can execute several conda commands within a single process. In this case, the internal state carries over and can sometimes lead to unexpected results (e.g. the cache becomes outdated as commands are performed). Of course, it should be possible for conda to handle this internal state directly. My point is just that using conda this way is not the main focus of the developers. If you want the most reliable method, use conda the way the developers intend it to be used -- as its own process.

conda is a fairly slow command, so I don't think one should worry about the performance impact of calling a subprocess. As I noted in another comment, pip is a similar tool to conda and explicitly states in its documentation that it should be called as a subprocess, not imported into Python.

I found that conda.cli.python_api and conda.api are limited, in the sense that, they both don't have the option to execute commands like this:

conda export env > requirements.txt

So instead I used subprocess with the flag shell=True to get the job done.

subprocess.run(f"conda env export --name {env} > {file_path_from_history}",shell=True)

where env is the name of the env to be saved to requirements.txt.

The simpler thing that i tried and worked for me was :

import os

try:
    import graphviz
except:
    print ("graphviz not found, Installing graphviz ")
    os.system("conda install -c anaconda graphviz")
    import graphviz

And make sure you run your script as admin.

Try this:

!conda install xyzpackage

Please remember this has to be done within the Python script not the OS prompt.

Or else you could try the following:

import sys
from conda.cli import main

    sys.exit(main())

    try:
        import conda
        from conda.cli import main
        sys.argv = ['conda'] + list(args)
        main()