You can use the following code to generate a requirements.txt file:

pip install pipreqs

pipreqs /path/to/project

more info related to pipreqs can be found here.

Sometimes you come across pip freeze, but this saves all packages in the environment including those that you don't use in your current project.

For python3: (I have both python 2 and 3 on my machine, where python2 is the default)

# install
pip3 install pipreqs

# Run in current directory
python3 -m  pipreqs.pipreqs .

python2:

pip install pipreqs
python -m  pipreqs.pipreqs .

To check your python version:

python --version

In my case, I use Anaconda, so running the following command from conda terminal inside my environment solved it, and created this requirements.txt file for me automatically:

conda list -e > requirements.txt

This was taken from this Github link pratos/condaenv.txt

If an error been seen, and you are using anaconda, try to use the .yml option:

conda env export > <environment-name>.yml

For other person to use the environment or if you are creating a new enviroment on another machine:

conda env create -f <environment-name>.yml

.yml option been found here

To create a requirement Python module list, write this code in your terminal:

pip3 freeze > requirements.txt

Kinda mind-blowing how this simple task is so complicated in Python. Here is what I think is the best way to do it automatically.

You need two tools:

1.pipreqs

pip3 install pipreqs

pipreqs will go through your project and only install the packages that your project use. Instead of all the packages in your python environment as pip freeze would do.

But there's a problem with this approach. It does not install the sub-packages.

For example, your project uses pandas==1.3.2. pandas itself uses numpy==1.21.2 among other packages. But pipreqs itself does not write the sub-packages (i.e. numpy) in requirments.txt

This is where you need to combine pipreqs with the second tool.

2. pip-tools

pip3 install pip-tools

pip-tools will take the packages in requirements.in and generate the requirements.txt with all the sub-packages. For example, if you have pandas==1.3.2 in requirements.in, pip-tools would generate

numpy==1.21.2 # via pandas in requirements.txt.

But you need to manually add the package in requirements.in. Which is prone to mistake and you might forget to do this once in a while.

This is where you can use the first tool.

But both the tools write to requirements.txt. So how do you fix it?

Use the --savepath for pipreqs to write in requirements.in instead of the default requirements.txt.

To do it in one command; just do

pipreqs --savepath=requirements.in & pip-compile

There you go. Now you don't need to worry about manually maintaining the packages and you're requirements.txt will have all the sub-packages so that your build is deterministic.

TL;DR

1. pip3 install pipreqs
2. pip3 install pip-tools

Use the following to build a deterministic requirements.txt

pipreqs --savepath=requirements.in && pip-compile

Firstly, your project file must be a py file which is direct python file. If your file is in ipynb format, you can convert it to py type by using the line of code below:

jupyter nbconvert --to=python

Then, you need to install pipreqs library from cmd (terminal for mac).

pip install pipreqs

Now we can create txt file by using the code below. If you are in the same path with your file, you can just write ./ . Otherwise you need to give path of your file.

pipreqs ./

or

pipreqs /home/project/location

That will create a requirements.txt file for your project.

I blindly followed the accepted answer of using pip3 freeze > requirements.txt

It generated a huge file that listed all the dependencies of the entire solution, which is not what I wanted.

So you need to figure out what sort of requirements.txt you are trying to generate.

If you need a requirements.txt file that has ALL the dependencies, then use the pip3

pip3 freeze > requirements.txt

However, if you want to generate a minimal requirements.txt that only lists the dependencies you need, then use the pipreqs package. Especially helpful if you have numerous requirements.txt files in per component level in the project and not a single file on the solution wide level.

pip install pipreqs
pipreqs [path to folder]
e.g. pipreqs .
     pipreqs . --force --ignore=tests (Overwrites exisiting requirements.txt, ignores the tests directory)

Make sure to run pip3 for python3.7.

pip3 freeze >> yourfile.txt

Before executing the above command make sure you have created a virtual environment.

python3:

pip3 install virtualenv
python3 -m venv <myenvname> 

python2:

pip install virtualenv
virtualenv <myenvname>

After that put your source code in the directory. If you run the python file now, probably it won't launch if you are using non-native modules. You can install those modules by running pip3 install <module> or pip install <module>.

This will not affect you entire module list except the environment you are in.

Now you can execute the command at the top and now you have a requirements file which contains only the modules you installed in the virtual environment. Now you can run the command at the top.

I advise everyone to use environments as it makes things easier when it comes to stuff like this.

If Facing the same issue as mine i.e. not on the virtual environment and wants requirements.txt for a specific project or from the selected folder(includes children) and pipreqs is not supporting.

You can use :

import os
import sys
from fuzzywuzzy import fuzz
import subprocess

path = "C:/Users/Username/Desktop/DjangoProjects/restAPItest"


files = os.listdir(path)
pyfiles = []
for root, dirs, files in os.walk(path):
      for file in files:
        if file.endswith('.py'):
              pyfiles.append(os.path.join(root, file))

stopWords = ['from', 'import',',','.']

importables = []

for file in pyfiles:
    with open(file) as f:
        content = f.readlines()

        for line in content:
            if "import" in line:
                for sw in stopWords:
                    line = ' '.join(line.split(sw))

                importables.append(line.strip().split(' ')[0])

importables = set(importables)

subprocess.call(f"pip freeze > {path}/requirements.txt", shell=True)

with open(path+'/requirements.txt') as req:
    modules = req.readlines()
    modules = {m.split('=')[0].lower() : m for m in modules}


notList = [''.join(i.split('_')) for i in sys.builtin_module_names]+['os']

new_requirements = []
for req_module in importables:
    try :
        new_requirements.append(modules[req_module])

    except KeyError:
        for k,v in modules.items():
            if len(req_module)>1 and req_module not in notList:
                if fuzz.partial_ratio(req_module,k) > 90:
                    new_requirements.append(modules[k])

new_requirements = [i for i in set(new_requirements)]

new_requirements

with open(path+'/requirements.txt','w') as req:
    req.write(''.join(new_requirements))

P.S: It may have a few additional libraries as it checks on fuzzylogic.

best way for Python 3 is:

pip3 freeze > requirements.txt

it worked for me...

If you have installed many dependencies in your system and you need requirements.txt for a specific project, you can install first pipreqs:

$ pip install pipreqs

and execute the below command under the project folder.

$ pipreqs

This command will generate requirements.txt file for the particular project.

Simple Pythonic Way

To get a list of all the REQUIREMENTS in a standard requirements.txt file, you can use the following command.

pip freeze > requirements.txt

Now, this should automatically create a standard requirements file with all of the packages installed alongside their corresponding versions.

Pretty Print on Terminal

If you just want to get a pretty print on the terminal you can use the following approach.

pip list

This lists all of the installed packages, in a pretty print format.

Custom Dependency

If you have a project folder like say, a Github Repo, and you want to get a custom requirements.txt for project You can use the following Package. pipreqs