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cannot use pyperclip module in python shell after successful download [duplicate]

During the past years, I have installed many Python libraries with various Python versions. To make them ready to work immediately, I installed them blindly without control. Currently they're causing problems when I tried to install pynest which invokes numpy, scipy and matplotlib. After struggling, I am going to clean and reinstall Python and the libraries.
After investigation, I found Python 2.5/2.6/2.7/3.2 on my system, and each of them has some copies or other things at: (my OS == Mac OS X 10.7.5 Lion)
/Library/Frameworks/
/opt/local/Library/Frameworks/
/opt/local/bin/
/Applications/
/usr/local/bin/
/usr/bin/
/System/Library/Frameworks/
I know I'm crazy to have these. Now I have removed all these except the things in /System/Libarary/Frameworks (I never remove any thing from /System/Library/). After the clean work, which python now gives /usr/bin/python which links to /System/Library/Frameworks.
Now, is it a clear environment for me to reinstall python? How to double check that there's no other versions existing? How should I reinstall them to guarantee that they and their libraries won't be everywhere and have many copies again?
I want to install a clean Python 2.7 onto a proper location, and make my system know exactly where it is and never install any libraries somewhere else. Please give me some advice that how to manage it like in a professional way.
For your information, here is my current $PATH, I think it should be modified:
/opt/local/bin:/opt/local/sbin:/opt/nest/lib/python2.7/site-packages:/usr/local/lib/python2.7/site-packages:/Library/Frameworks/Python.framework/Versions/2.7/bin:/usr/texbin:/Library/Frameworks/Python.framework/Versions/3.2/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/texbin:/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/django/bin:/usr/X11/bin:/opt/local/bin:/opt/local/sbin:/usr/local/lib/python2.7/site-packages:/Library/Frameworks/Python.framework/Versions/2.7/bin:/Library/Frameworks/Python.framework/Versions/3.2/bin
Please let me know If you need more information. Thank you!
UPDATE:
I'm rethinking profoudly why it becomes so crazy. I believe it's because I installed things via:
easy_install / macports / homebrew / fink / pip sometimes;
.dmg sometimes;
.pkg sometimes;
compile source code sometimes;
and they made things at different locations. I wonder what's the mechanism behind these ways? How do they choose target location? How to prevent them from messing things up?

Why did it get messed up?
There're a couples of different way to install Python, as the update of OP says, and they locate files in different locations. For example, macports puts things into /opt/local/, while homebrew puts things into /usr/local/. Also, Mac OS X brings a few python versions with itself. So, if you install python many times via different ways, you will get many python versions existing independently on your system.
What problem does it cause?
I don't know exactly. I guess the problem is that if you have many versions of python, then which one to use and where to find packages will be determined by the path order in your system PATH and the PYTHONPATH respectively. So you may lose control of where to install python modules. Consider that if you run sudo python setup.py install to install a module (it finds python by the root's PATH) and then try to import the module by python -c "import it" (this time it finds python by your PATH), maybe something will go wrong. This is my guess, I didn't validate it. But in my own case, something did go wrong.
How to avoid this?
I think the principle would be that be aware of that different ways and tools install things independently to different locations, so use them mindfully.
Unless you intend to, don't install the same thing twice via different
ways. (If you intend to do it for python, you might want to check out virtualenv)
Keep an eye on the path order in your PATH and consider if it's
correct.
When installing modules, be clear which python (or pip) is
running and where the module is installed.
So, how did I solve my own case?
Since it had been messing up already and seemed to be very hard to cure, so finally I solved this question by a full OS re-installation, and started to follow the DOs-and-DONTs above. For the installation of the scientific environment with python (numpy/scipy/matplotlib, which had shown problems to make me ask this question), I found this tutorial was extremely helpful. So, problem solved finally.

Here is what was confusing me and how I solved it.
$ which python
/usr/bin/python
$ which python3
/usr/local/bin/python3
$ ls /usr/local/bin/python
ls: /usr/local/bin/python: No such file or directory
So notice I didn't have a HomeBrew installation of python2.7, but did have the python3 installation. The version under /usr/bin/python is using the system default. You can tell based on the module search path:
$ /usr/bin/python
Python 2.7.10 (default, Feb 7 2017, 00:08:15)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
`enter code here`Type "help", "copyright", "credits" or "license" for
more information.
>>> import sys
>>> sys.path
['', '/Library/Python/2.7/...
Notice the '/Library/Python'... that's Mac OS's version of python. But I want to stay strictly on a user installed version (i.e. HomeBrew).
So here's what I did to fix this:
$ brew install python
...
Warning: python 2.7.13 is already installed, it's just not linked.
You can use `brew link python` to link this version.
$ brew link --overwrite python
$ which python
/usr/local/bin/python
$ python
Python 2.7.10 (default, Feb 7 2017, 00:08:15)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.path
['', '/usr/local/Cellar/python/2.7.13...
Its no longer /Library/.. but /usr/local.
Now its finding all of my pip installed modules! Problem solved!
UPDATE:
After updating brew to version 1.5.4, it seems the symbolic links were removed. And now you have to add this to your path:
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
Read the Caveats section in 'brew info python':
==> Caveats
This formula installs a python2 executable to /usr/local/bin.
If you wish to have this formula's python executable in your PATH then add
the following to ~/.bash_profile:
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
Pip and setuptools have been installed. To update them
pip2 install --upgrade pip setuptools
You can install Python packages with
pip2 install <package>
They will install into the site-package directory
/usr/local/lib/python2.7/site-packages
See: https://docs.brew.sh/Homebrew-and-Python.html

In order to install a python distributions into specific folder, you can use the --prefix scheme during python installation. Using the prefix scheme, you can for example install Python 2.7 into the folder /opt/py27. Now, in order to use the new installed Python distribution you have to: cleanup you PATH and LD_LIBRARY_PATH:
Remove all 'old' Python paths and
configure (according to my example) the environment variables like this:
PATH: Add /opt/py27/bin
LD_LIBRARY_PATH: Add /opt/py27/lib
That's it.
(In case you need multiple environments of Python installed at the same time, I'd suggest to have a look at virtualenv)

tl;dr
brew install python
Symptoms
I had similar issues with python programs not finding dependencies.
My python3 version was a broken symlink.
My pip was pointing to a python 3.8
And my pip3 was pointing to 3.9
python -V was outputting some python 2.7 version
python3 -V was outputting some python3.8 version
Solution
I ran brew install python and it fixed all my problems.

How to install Python 3.8.1 on RHEL 8 UBI container with dnf?

How do I install and run Python 3.8.1 on Linux? Python.org does not offer a Linux binary for Python 3.8.1.
I want to type:
dnf -y install python or dnf -y install python38
and have it install Python 3.8.1 on my RHEL 8.0 or 8.1 inside my minimal container that I want to keep small.
How would I make this happen?
I don't even see a download for Python for Linux on python.org.
Do people use Python on Linux?
There are no Linux binaries to be downloaded from Python.org
I have searched all over (internet search), and cannot find a way to install Python 3.8.1 easily on a minimal container.
I do not want to download the source and compile, because it is a small container that I am trying to keep small without a lot of overhead.
Reference:
https://www.python.org/downloads/release/python-381/

Two notes: I'm not sure how your container is set. You've tagged this as both RHEL and Fedora. These are two separate distributions. I can comment on Fedora.
Firstly, yes, Python is heavily used in the GNU/Linux world. Most distros use it as one of the languages to build the system and its packages. Linux servers are the only officially recommended servers for Python, or so I've read (will edit with source later if I can find it). Python.org does have Linux downloads, but in source files, packaged in compressed tarballs. This can promote searching the distro package manager first for distro compatibility (since being in a distro's repo should mean the version was vetted); these packages are precompiled unless otherwise specified. It also means the files are distro agnostic -- no need for .DEB, .RPM...
Fedora: There isn't a Fedora version listed in the post, but at least Fedora 31 has a development version, as they call it, of Python 3.8.1 in RPM format. (Fedora 32 is slated to have Python 3.8 at the system level.) You can get it with:
sudo dnf install python38
Be sure not to overwrite the system variables for python or python3; this mistake can cause systemic issues of varying magnitude. Once installed, you can create a virtual environment in whichever directory you'd like with:
python3.8 -m venv <venv_name>
To activate the venv, use:
. <path/to/venv>/<venv_name>/bin/activate
You can set an alias or symlink for ease. When the venv is activated, Python 3.8.x will be the Python version used when the interpreter is called. You should see your venv_name in parentheses, to the left of your PS1. To deactivate, use:
deactivate
The venv_name should be removed from the PS1, returning it to normal. Checking the Python version should return the system-level Python version.
If you check your Python version before and after the activation, it should be different.
python3 -V
This package may or may not have been sent downstream to RHEL. If you have the package available but want the full Python stack, or if it isn't available in RHEL's baseline repos, you may need to grab the source files and unpack the tarballs.
Alternatives are checking other repos, seeing about RPMs that someone else compiled from source, or checking out flatpak (which I haven't done).
Last note: compiling from source shouldn't result in a larger Python binary. You can delete any unnecessary extras, like the original archive file used for compiling, after you've extracted what you need. The action itself will only be stored in volatile memory, not on your disk.

pip installed module but python gives Import error [duplicate]

During the past years, I have installed many Python libraries with various Python versions. To make them ready to work immediately, I installed them blindly without control. Currently they're causing problems when I tried to install pynest which invokes numpy, scipy and matplotlib. After struggling, I am going to clean and reinstall Python and the libraries.
After investigation, I found Python 2.5/2.6/2.7/3.2 on my system, and each of them has some copies or other things at: (my OS == Mac OS X 10.7.5 Lion)
/Library/Frameworks/
/opt/local/Library/Frameworks/
/opt/local/bin/
/Applications/
/usr/local/bin/
/usr/bin/
/System/Library/Frameworks/
I know I'm crazy to have these. Now I have removed all these except the things in /System/Libarary/Frameworks (I never remove any thing from /System/Library/). After the clean work, which python now gives /usr/bin/python which links to /System/Library/Frameworks.
Now, is it a clear environment for me to reinstall python? How to double check that there's no other versions existing? How should I reinstall them to guarantee that they and their libraries won't be everywhere and have many copies again?
I want to install a clean Python 2.7 onto a proper location, and make my system know exactly where it is and never install any libraries somewhere else. Please give me some advice that how to manage it like in a professional way.
For your information, here is my current $PATH, I think it should be modified:
/opt/local/bin:/opt/local/sbin:/opt/nest/lib/python2.7/site-packages:/usr/local/lib/python2.7/site-packages:/Library/Frameworks/Python.framework/Versions/2.7/bin:/usr/texbin:/Library/Frameworks/Python.framework/Versions/3.2/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/texbin:/Library/Frameworks/Python.framework/Versions/3.2/lib/python3.2/site-packages/django/bin:/usr/X11/bin:/opt/local/bin:/opt/local/sbin:/usr/local/lib/python2.7/site-packages:/Library/Frameworks/Python.framework/Versions/2.7/bin:/Library/Frameworks/Python.framework/Versions/3.2/bin
Please let me know If you need more information. Thank you!
UPDATE:
I'm rethinking profoudly why it becomes so crazy. I believe it's because I installed things via:
easy_install / macports / homebrew / fink / pip sometimes;
.dmg sometimes;
.pkg sometimes;
compile source code sometimes;
and they made things at different locations. I wonder what's the mechanism behind these ways? How do they choose target location? How to prevent them from messing things up?

Why did it get messed up?
There're a couples of different way to install Python, as the update of OP says, and they locate files in different locations. For example, macports puts things into /opt/local/, while homebrew puts things into /usr/local/. Also, Mac OS X brings a few python versions with itself. So, if you install python many times via different ways, you will get many python versions existing independently on your system.
What problem does it cause?
I don't know exactly. I guess the problem is that if you have many versions of python, then which one to use and where to find packages will be determined by the path order in your system PATH and the PYTHONPATH respectively. So you may lose control of where to install python modules. Consider that if you run sudo python setup.py install to install a module (it finds python by the root's PATH) and then try to import the module by python -c "import it" (this time it finds python by your PATH), maybe something will go wrong. This is my guess, I didn't validate it. But in my own case, something did go wrong.
How to avoid this?
I think the principle would be that be aware of that different ways and tools install things independently to different locations, so use them mindfully.
Unless you intend to, don't install the same thing twice via different
ways. (If you intend to do it for python, you might want to check out virtualenv)
Keep an eye on the path order in your PATH and consider if it's
correct.
When installing modules, be clear which python (or pip) is
running and where the module is installed.
So, how did I solve my own case?
Since it had been messing up already and seemed to be very hard to cure, so finally I solved this question by a full OS re-installation, and started to follow the DOs-and-DONTs above. For the installation of the scientific environment with python (numpy/scipy/matplotlib, which had shown problems to make me ask this question), I found this tutorial was extremely helpful. So, problem solved finally.

Here is what was confusing me and how I solved it.
$ which python
/usr/bin/python
$ which python3
/usr/local/bin/python3
$ ls /usr/local/bin/python
ls: /usr/local/bin/python: No such file or directory
So notice I didn't have a HomeBrew installation of python2.7, but did have the python3 installation. The version under /usr/bin/python is using the system default. You can tell based on the module search path:
$ /usr/bin/python
Python 2.7.10 (default, Feb 7 2017, 00:08:15)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
`enter code here`Type "help", "copyright", "credits" or "license" for
more information.
>>> import sys
>>> sys.path
['', '/Library/Python/2.7/...
Notice the '/Library/Python'... that's Mac OS's version of python. But I want to stay strictly on a user installed version (i.e. HomeBrew).
So here's what I did to fix this:
$ brew install python
...
Warning: python 2.7.13 is already installed, it's just not linked.
You can use `brew link python` to link this version.
$ brew link --overwrite python
$ which python
/usr/local/bin/python
$ python
Python 2.7.10 (default, Feb 7 2017, 00:08:15)
[GCC 4.2.1 Compatible Apple LLVM 8.0.0 (clang-800.0.34)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sys
>>> sys.path
['', '/usr/local/Cellar/python/2.7.13...
Its no longer /Library/.. but /usr/local.
Now its finding all of my pip installed modules! Problem solved!
UPDATE:
After updating brew to version 1.5.4, it seems the symbolic links were removed. And now you have to add this to your path:
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
Read the Caveats section in 'brew info python':
==> Caveats
This formula installs a python2 executable to /usr/local/bin.
If you wish to have this formula's python executable in your PATH then add
the following to ~/.bash_profile:
export PATH="/usr/local/opt/python/libexec/bin:$PATH"
Pip and setuptools have been installed. To update them
pip2 install --upgrade pip setuptools
You can install Python packages with
pip2 install <package>
They will install into the site-package directory
/usr/local/lib/python2.7/site-packages
See: https://docs.brew.sh/Homebrew-and-Python.html

In order to install a python distributions into specific folder, you can use the --prefix scheme during python installation. Using the prefix scheme, you can for example install Python 2.7 into the folder /opt/py27. Now, in order to use the new installed Python distribution you have to: cleanup you PATH and LD_LIBRARY_PATH:
Remove all 'old' Python paths and
configure (according to my example) the environment variables like this:
PATH: Add /opt/py27/bin
LD_LIBRARY_PATH: Add /opt/py27/lib
That's it.
(In case you need multiple environments of Python installed at the same time, I'd suggest to have a look at virtualenv)

tl;dr
brew install python
Symptoms
I had similar issues with python programs not finding dependencies.
My python3 version was a broken symlink.
My pip was pointing to a python 3.8
And my pip3 was pointing to 3.9
python -V was outputting some python 2.7 version
python3 -V was outputting some python3.8 version
Solution
I ran brew install python and it fixed all my problems.

The location of standard Python libraries?

It is stated in Python documentation here that:
By default, the libraries are searched in prefix/lib/pythonversion and exec_prefix/lib/pythonversion, where prefix and exec_prefix are installation-dependent directories, both defaulting to /usr/local.
But when I looked into my /usr/local directory, what I found was a folder named python2.7. I did install python3.5 not python2.7 on my device (MacBook mid 2012).

You could use sys module to find that.
import sys
print sys.path
Ouput like:
['', '/usr/local/lib/python2.7/dist-packages/mccabe-0.3.1-py2.7.egg', ...

Mac comes with a default Python 2.7 installation. Your installation did not remove python2.7. Probably also the reason why the system libraries are not under usr/local.

You never state how you attempted to install Python 3.5 onto your MacBook, depending on the installation options you used while building the Python source (or the bundle you downloaded) the install location could be different from the defaults. If you provide further details on your installation method, it will be easier to answer all aspects of your question.
As far as I can tell, Apple does not use the installation defaults to provide Python with OSX. On my OSX El Capitan machine, I can see the system Python library at /System/Library/Frameworks/Python.framework/Versions/2.7 and the binary at /usr/bin/python (Python 2.7.x comes preinstalled for all recent versions of OSX).
It looks like the easiest way to get Python 3.5 on Mac is to use MacPython which will install alongside the system version of Python (as you should not alter the default system version of Python or risk breaking OSX). It installs some helper applications into your Finder's Applications directory and installs the library files to /System/Library/Frameworks/Python.framework/Versions/3.5. Since you will have more then one version of Python installed, you would also need to put some effort into making sure your scripts are using the proper version.
If you have a /usr/local/python2.7 directory, that sounds like something that was previously installed by a user. If I remember correctly, OSX does not normally use /usr/local for system software.
Hope that helps

How to install python 2.7.4 on OSX Mountain Lion

I tried installing python 2.7.4 by overwriting the native Apple's installation of python 2.7 by following this link (wolfpaulus.com), and as a result both easy_install and pip no longer work.
This link (apple.com) suggests the native Apple bundle should never be deleted.
Is it possible to restore python 2.7 supplied by Apple without reinstalling OSX?
Is there a definitive guide to upgrading python to 2.7.4 on OSX Lion? For instance, before breaking my set up I could install bumpy, django into 2.7.4, but matplotlib refused to install to anything but 2.7, either from binaries or source.
Thanks.

It is absolutely not a good idea to replace Apples default python installation. If you have done, then you could try with the following command
" brew install python --framework "
R

You should never remove anything in /System/Library or /usr (other than /usr/local). Files installed in those locations are managed by Apple as part of OS X. At worst you can fatally damage your OS X system; at best you are at risk of all of your changes being wiped out by the next software update. In particular with Python, you’ve just wiped out Apple-supplied extensions to Python that are not available elsewhere. The right way to update a system component like Python is to install the new version at a different location, like the python.org Python installers do in /Library/Frameworks, and then manage access by modifying your shell PATH environment variable. Unfortunately, Apple does not make it easy to install individual components of OS X that have been mistakenly removed. To properly restore all of the system Python that you've deleted, the easiest approach is to reinstall OS X itself.
When you install another version of Python, you should also use it to install additional versions of pip or easy_install. Generally, each Python version should have its own version of each.