Develop Reference

Why can't Python find the module I installed?

Presently I'm using Python on a Windows system. I installed Python 3.10 from Anaconda and also the Pycharm IDE. I have ensured that Python is in the correct path in the environment variable. I have also replicated this problem using two different versions of Python, 3.10 and 3.9.
Very simply, in PyCharm, I open a terminal and type
conda install -c numpy numpy.
Then, I write a new "main.py" script. I have one line: "import numpy". I receive the error:
Traceback (most recent call last):
File "C:\Users\---\PycharmProjects\pythonProject3\main.py", line 17, in <module>
import numpy
ModuleNotFoundError: No module named 'numpy'
What am I doing wrong?
Going on advice from a friend, I created a new PyCharm project sitting not in my user directory but on the C: drive, and got the same error. Finally, when trying to re-install the package using either using either pip or conda, I get this message:
# All requested packages already installed.

You have 2 versions of Python:
Default Python (used everytime you open your command prompt and type python or python3)
Anaconda is installing packages in a virtual environment, using it's own Python (it is located in a different path)
You can see the path of your installed python using python -c "import os, sys; print(os.path.dirname(sys.executable))"
You have 2 Options:
Configure the PyCharm in order to use the anaconda Python. https://www.jetbrains.com/help/pycharm/configuring-python-interpreter.html#view_list
Open a command prompt in the project's folder (you can do it easily using PyCharm). Type conda env list. This will show you all available anaconda virtual environments. Choose 1 of them and type conda activate <env_name>, where <env_name>=the name of the environment. Then, run your program using python <name_of_your_program>
You can see the paths where the anaconda environments and packages are installed using conda info

There main reason for this is
You are running your main.py in different environment rather than where you installed numpy.
If you trying to run it via cmd use this method
Check which environment you are in right now. refer this and
this. But the most easiest way to do this is use where command
in windows cmd. C:\> where python or C:\> where python3. You will
get the path of activated interpreter.
list conda envs - conda env list
activate conda env - conda activate <env name>
then run this command. pip freeze . and check is there numpy in
the list. If not you have to find and activate the environment where
you have installed numpy.
If you want to run it in pycharm
Refer this on how to change pycharm interpreter.
https://www.jetbrains.com/help/pycharm/configuring-python-interpreter.html

Many things can cause this, usually its one of these
You may have to restart your terminal, or IDE if running in there, after installing a package to "refresh" the environmental path
The package is not in the environmental path

No module named 'sportsreference'

I pip installed the sportsreference package in my command prompt and it shows successful. Yet when I try to call it in my Jupyter Notebook it says no module named sportsreference.
Any help on what I'm doing wrong?

The interpreter that your Jupyter uses to run the cells is not the one you installed that package into. Remember you can have not only different versions of Python interpreter, but also different virtual environments associated with each Python interpreter in your machine.
So either install the package in the interpreter that Jupyter uses, or run the Jupyter from the interpreter you've installed that package into.
The simplest solution is to install it in a Jupyter cell with:
!pip install <your_package_name>
the ! allows you to execute command.
To check which interpreter currently runs your code you can check the output of:
import sys
print(sys.executable)

Installed Python 3, now my Anaconda environment is messed up

I apologize in advance for my poor vocabulary - I do not know much about environments, paths, and things of the sort. I am on macOS Catalina.
I created a program using Spyder from Anaconda. My program uses packages like pandas and numpy which are built into Anaconda. I used to be able to run the program in Terminal with the command: $ python3 app.py.
However, I recently downloaded Python 3.9.1 from https://www.python.org/downloads/mac-osx/. Ever since then, I have been unable to run the program in Terminal because of missing package errors like
import numpy as np
ModuleNotFoundError: No module named 'numpy'
I went to my applications folder, right clicked on Python 3.9.1, and clicked Move To Trash. This did not solve my problem. I reinstalled Anaconda (I did not uninstall it - just simply installed again), but that also did not solve my problem. I am able to run the program in Spyder (from Anaconda), but I wish to run it in Terminal again.
I believe the solution is simple, but I am not sure what to do. I have tried searching and reading but I am not familiar with the terminology. I think I just need to reset the environment, but I am not sure.

Anaconda is used for creating closed enviorments, so you don't need to thrash your computer with global packages.
Imagine you have 2 different projects. Project A works only on python 3.2 and Project B works on 3.8.
That's where anaconda comes in.Managing enviorments with conda
conda create -n PROJECTA python=3.2
conda create -n PROJECTB python=3.8
Now activate env you wish to work with. For macOS
source activate PROJECTA
Now you should see (PROJECTA) instead of (base)
Now inside this PROJECTA you can install modules you require like
pip install numpy
and when executing .py file
move to dir with your app.py file and
python3 app.py
this will be opened in conda enviorment you created and activated, using modules you installed in this env.
You can still edit py file and execute it through shell, but it will throw errors if you try to run it from IDE without linking project to respected conda enviorment.
If you are using PyCharm Configure a Conda vir env in PyCharm

You must create separate environments for every projects or it will get messed up.
conda create -n name_of_environment python=3.6
You must not delete the python folder into trash rather uninstall it Python 3.9.1 and remove its path from the directory.
In short if you run python from terminal and it is not supporting your Installed anaconda packages . You should use anaconda prompt instead of CMD.
Because your anaconda is not added to path rather then it picks up the python 3.9 you have installed from Python 3.9.1 from https://www.python.org/downloads/mac-osx/. ( This is the python with separate environment then anaconda so it wont detect anaconda packages ).
When you run the cmd and enter python it runs the python that you downloaded and installed rather then Anaconda
At the time of installing anaconda it gives option to add conda variables to path you can select those at installing stage / or add manually

Pip not installing Python modules to proper directory

So I downloaded a module, but when I tried to use it in a program, Python threw the error:
"ImportError: No module named markovify"
When I go to try to change my .bash_profile, it shows this:
"# Setting PATH for Python 3.5
The orginal version is saved in .bash_profile.pysave
PATH="/Library/Frameworks/Python.framework/Versions/3.5/bin:${PATH}"
export PATH"
I've been using 2.7.10 all this time, and Terminal defaults to it. (When I type in Python, that's the version it says I'm using)
I'm trying to get pip to install modules for python 2.7.10 to a different folder.
What's weird is this: I seem to have installed pyparsing with pip and it seems to work. I tried installing markovify and it throws this error message.
What am I missing?

When I go to try to change my .bash_profile, it prints this
That suggests you're using some tool to change your profile. Did you also use that tool to install markovify? You need to be clear about your environment when you have environment questions! :-)
If you installed markovify from the command line, I'd suggest opening a new terminal and running these commands, just to make sure you're working from where you think you are:
$ python --version
Python 2.7.10
$ command -v python
/usr/bin/python
The most likely problem, it seems to me, is that you got a bit tangled up and wound up doing something other than what you intended. From a fresh start, provided you're starting with the environment you want, pip should, you know, Just Work.
I'm trying to get pip to install modules for python 2.7.10 to a different folder.
That's possible to do, but are you sure that's what you want? Usually if you're using the Python interpreter you intend to, and haven't putzed with PYTHON_PATH & friends, when you run pip, it will install to its default location, which sure enough is where Python will look for it when you say to import it.
As an experiment, you might check if markovify was somehow installed for Python 3.5. Try
$ /Library/Frameworks/Python.framework/Versions/3.5/bin/python -c 'import markovify'
(You might also want to check that the Python interpreter is in fact in that folder and has that name.)

When you're working on more than one Python version, you should work on Virtual Environments:
Virtual Env on Hitchhiker's Guide

Package installed by Conda, Python cannot find it

I try to install Theano by Anaconda. It works, but when I enter the python -i, import theano shows No module named 'theano'. Do I need to switch another interpreter of Python, how? Also, for the packages installed by conda, if I don't double install them, can I find in Python? How is Python related to Python by Anaconda? Thanks!!!

I had have a similar issue, trying to install folium. If you are using the Anaconda:
When you install using conda install -c conda-forge folium, the package will be placed in:
./anaconda3/envs/[name env]/lib/python3.7/site-packages/folium
When you install using pip (with a anaconda env activated), pip install folium, the package will be placed in:
./anaconda3/lib/python3.7/site-packages/folium
Python use first the sites-packages as the target directory of manually built python packages. When you build and install python packages from source (using distutils, probably by executing python setup.py install ), you will find the installed modules in site-packages by default.
In this case you have two places: /anaconda3/lib/python3.7/site-packages/ and /anaconda3/envs/[name env]/lib/python3.7/site-packages/.
First the modules will be available as default in /anaconda3/lib/python3.7/site-packages/. Sometimes (and I really don't know why) the modules inside sites-packages conda env are not available to import automatically without export the PATH.
So, to solve this issue, you have 2 options:
Installing using pip install folium and import folium (don't need install by conda install), or
After conda install , run conda init, close the terminal and open a new one. So, try to import again.
Here are some tips about use a pip in a conda-environment.

You can refer to a specific version of python by using the following at the first line of your .py file
This is for python 2.7
#!/usr/bin/env python2.7
This is for python 3
#!/usr/bin/env python3
As other users already pointed out you need to check if your module is included in your sys path. Use code:
import sys
print(sys.path)
If not you can include this in your sys.path by using the command:
sys.path.append('/path/to/the/folder/of/your/module/file')
or place it in default PYTHONPATH itself.
Other great answers:
https://stackoverflow.com/a/19305076/5381704

The problem is that in the code editor you are using, you are running the default interpreter. Based on your code editor, change the python interpreter to the conda interpreter and it will work.

In my case that happened because conda screwed up the environment variables. Instead of using env-specific python and pip, it used the globally installed ones.
Solution:
conda deactivate your-env
conda activate your-env

In my workstation, I was able to solve No module named <module name> error using two different ways.
First method, I solved this temporarily by:
(1) Open a Terminal
(2) $ conda activate <Conda environment name>
(3) $ export PYTHONPATH=/home/<user name>/anaconda3/envs/<Conda environment name>/lib/<Python package version>/site-packages:$PYTHONPATH
It is a temporary solution. Whenever you run your virtual environment, you have to do this.
My runtime environment:
    OS: Unbuntu 18.04
    Conda version: 4.8.2
    Conda-build version: 3.18,11
    Python version 3.7.6.final.0
Second method, I removed the
alias python=/usr/bin/python3.6 line in bashrc file.
Somehow this line blocks using Python tools installed in Anaconda Virtual Environment if the Python version in the Virtual Environment is different.