Setting up Conda environment for a project

Step 1. You will create a new environment in Anaconda prompt.

conda create --name myenv

Ref: https://docs.conda.io/projects/conda/en/latest/user-guide/tasks/manage-environments.html#creating-an-environment-with-commands

Step 2. Then we install "pip" to do some installations that are available in PyPI but not in Conda repos.

conda install pip

Note: There are also packages that are not available in PyPI but are available in Conda.

LIST OF PYTHON PACKAGES THAT ARE NOT AVAILABLE THROUGH 'PIP'

ERROR: Could not find a version that satisfies the requirement conda==4.7.12 (from -r req.txt (line 36)) (from versions: 3.0.6, 3.5.0, 3.7.0, 3.17.0, 4.0.0, 4.0.1, 4.0.2, 4.0.3, 4.0.4, 4.0.5, 4.0.7, 4.0.8, 4.0.9, 4.1.2, 4.1.6, 4.2.6, 4.2.7, 4.3.13, 4.3.16)
ERROR: No matching distribution found for conda==4.7.12 (from -r req.txt (line 36))

###

conda==4.7.12
conda-build==3.18.9
conda-package-handling==1.6.0
conda-verify==3.4.2

Step 3. If you only want to upgrade a package, you can do that as follows:

(base) C:\Users\ashish\Desktop>pip install --upgrade flask

Step 4. Create a "requirements.txt" file (in the current working directory for your terminal) with some packages such as given below:
astor==0.8.0
astroid==2.3.1
astropy==3.2.1
atomicwrites==1.3.0

Step 5. Then you run the following command for "pip" or "conda" depending upon your required package:

conda install --file requirements.txt
pip install -r requirements.txt

UNRESOLVED / UNKNOWN ISSUES, AND SOME RESOLUTIONS: 

# If a package is already installed in your 'conda (base)' environment (as was the case for us with PyYAML), we got this error:
Installing collected packages: PyYAML, openapi-spec-validator, clickclick, connexion
  Found existing installation: PyYAML 3.13
Cannot uninstall 'PyYAML'. It is a distutils installed project and thus we cannot accurately determine which files belong to it which would lead to only a partial uninstall.

# Issue with "bitarray":
  LINK : fatal error LNK1158: cannot run 'rc.exe'
  error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\BIN\\x86_amd64\\link.exe' failed with exit status 1158

# Issue with "cffi":
  LINK : fatal error LNK1158: cannot run 'rc.exe'
  error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\BIN\\x86_amd64\\link.exe' failed with exit status 1158

# Issue with "cytoolz":
  cytoolz/dicttoolz.c(11394): error C2059: syntax error: ')'
  error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\BIN\\x86_amd64\\cl.exe' failed with exit status 2
 
# Failed to build astropy bitarray Bottleneck cffi cryptography Cython cytoolz Twisted

# Issue with "twisted.test.raiser"
  LINK : fatal error LNK1158: cannot run 'rc.exe'
  error: command 'C:\\Program Files (x86)\\Microsoft Visual Studio 14.0\\VC\\BIN\\x86_amd64\\link.exe' failed with exit status 1158
  
RESOLUTION (From link: https://stackoverflow.com/questions/14372706/visual-studio-cant-build-due-to-rc-exe):

Found this on Google... I would assume that in your case you would copy rc.exe and rcdll.dll to visual studio 2012\vc\bin or wherever you have it installed:

Part 2: FIX LINK : fatal error LNK1158: cannot run ‘rc.exe’

Add this to your PATH environment variables:

C:\Program Files (x86)\Windows Kits\8.0\bin\x86

Copy these files:

rc.exe
rcdll.dll

From

C:\Program Files (x86)\Windows Kits\8.0\bin\x86

To

C:\Program Files (x86)\Microsoft Visual Studio 11.0\VC\bin

Or I also found this:
Microsoft left a few things out of their MSVT package. Since no one knows whether they were left out by mistake or for license reasons, no one with MSVC is too interested in giving them out. A few Google searches turn up some tricky sources. Fortunately, Microsoft has finally wised up and solved this problem and many more.

http://msdn.microsoft.com/vstudio/express/support/faq/default.aspx#pricing

http://msdn.microsoft.com/vstudio/express/support/install/

A good amount of MSVT missing files are there but the missing SDK files aren't.

And this:::

I had the same problem which I solved by doing this:

Installing the Microsoft .Net Framework 2.0
Adding the path of the .NET Framework files (for me "C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727") to Global compiler settings > Programs > Additional Paths within Code::Blocks.
Now I can build and link resource files without errors.


POST RESOLUTION:

#### FOR TWISTED

Building wheels for collected packages: Twisted
  Building wheel for Twisted (setup.py) ... done
  Created wheel for Twisted: filename=Twisted-19.10.0-cp38-cp38-win_amd64.whl size=3087475 sha256=42d06847b471f115ae6925d43edef132d987b60bf5527e5ee99729872a99d0b4
  Stored in directory: c:\users\ashish\appdata\local\pip\cache\wheels\6c\7b\65\db0c3de94e8e87bd1600c617da06cbfcf18f449640bbe053e0
Successfully built Twisted
Installing collected packages: protego, Twisted, queuelib, scrapy