Develop Reference

Pip Errors Out When Installing Anything

I've run into an odd issue where pip just won't work. I'm using the latest version of PyCharm, and I've tried both Python 3.8.10 and 3.9.6.
I've done clean installations of both, removed from PATH, reinstalled with new installer, reinstalled pip, etc.
The error code I run into appears no matter what library I am trying to download. I've tried PyAudio, PyGame, OpenCV-Python and others.
Pip was working fine a couple days ago, and no changes have been made to any files in that time.
Attempting to run pip install --upgrade pip does not have an effect.
I've been running off virtual enviroments with setuptools 40.8.0 and pip 21.1.3 installed.
The full error for installing PyAudio can be seen here: https://pastebin.com/iQmZwsRv
PyGame error: https://pastebin.com/WEF8uM2d
OpenCV-Python Error: https://pastebin.com/LuZq99Cu

Py- audio - it's not compatible with your Py charm I suppose due to the latest install updates, try to install it on the main environment. Also, try to downgrade your version of python as many dependencies are not compatible with your version of python as stated by error[it is not compatible with this Python]
Open Cv - Fails to build the wheel package as it is attributed also in error [CMake was unable to find a build program corresponding to "Ninja". CMAKE_MAKE_PROGRAM is not set. You probably need to select a different build tool.]
May I know what build tool are you using?

How to make 'pip install' not uninstall other versions?

I am managing several modules on an HPC, and want to install some requirements for a tool using pip.
I won't use virtualenv because they don't work well with our module system. I want to install module-local versions of packages and will set PYTHONPATH correctly when the module is loaded, and this has worked just fine when the packages I am installing are not also installed in the default python environment.
What I do not want to do is uninstall the default python's versions of packages while I am installing module-local versions.
For example, one package requires numpy==1.6, and the default version installed with the python I am using is 1.8.0. When I
pip install --install-option="--prefix=$RE_PYTHON" numpy==1.6
where RE_PYTHON points to the top of the module-local site-packages directory, numpy==1.6 installs fine, then pip goes ahead and starts uninstalling 1.8.0 from the tree of the python I am using (why it wants to uninstall a newer version is beyond me but I want to avoid this even when I am doing a local install of e.g. numpy==1.10.1).
How can I prevent pip from doing that? It is really annoying and I have not been able to find a solution that doesn't involve virtualenv.

You have to explicitly tell pip to ignore the current installed package by specifying the -I option (or --ignore-installed). So you should use:
PYTHONUSERBASE=$RE_PYTHON pip install -I --user numpy==1.6
This is mentioned in this answer by Ian Bicking.

How to properly install wxPython?

So I was looking around at different things to do on Python, like code for flashing text or a timer, but when I copied them into my window, there were constant syntax errors. Now, maybe you're not meant to copy them straight in, but one error I got was 'no module named wx'. I learned that I could get that module by installing wxPython. Problem is, I've tried all 4 options and none of them have worked for me. Which one do I download and how do I set it up using Windows?
Thanks

It's on PyPI. As of wxPython 4, Python 3 is supported.
Unfortunately, PyPI has a package called wx that is stuck at version 3.0.3; be sure to install the package named wxpython instead.
pip install wxpython
Please note that pip will automatically build wxWidgets for you, but it will not install wxWidgets system dependencies such as GTK and OpenGLu. If the above command exits with an error, look above for a message like this:
checking for <something>... not found
checking for <something>... no
configure: error: <prereq> libraries not available
Error running configure
ERROR: failed building widgets
This should give you information about at least one of the packages your system is missing.
The "official" list of prerequisites from the wxWidgets source is:
dpkg-dev
build-essential
libjpeg-dev
libtiff-dev
libsdl1.2-dev
libgstreamer-plugins-base0.10-dev # or 1.0 if available
libnotify-dev
freeglut3
freeglut3-dev
libsm-dev
libgtk-3-dev
libwebkitgtk-3.0-dev # or libwebkit2gtk-4.0-dev if available
libxtst-dev
The actual package names provided by your package manager may not match these exactly, and to be honest, I don't really know the best way to query a package manager to determine what packages provide the libraries you need.

3 steps to install wx-widgets and pygame in python IDLE
Install python 3xxx in your system opting (Add 3xxx to your path).
open python CLI to see whether python is working or not.
then open command prompt (CMD).
type PIP to see whether pip is installed or not.
enter command : pip install wheel
enter command : pip install pygame
To install wxpython
enter command : pip install -U wxPython
Thats all !!

As per home page instruction:
Make sure you have at least version 6.0.8 of pip and 12.0.5 for setuptools.
Install requirements for Linux as outlined in the readme.rst at:
https://github.com/wxWidgets/Phoenix/blob/master/README.rst
Install wxPython-Phoenix (Linux):
sudo pip install --upgrade --trusted-host wxpython.org --pre -f http://wxpython.org/Phoenix/snapshot-builds/ wxPython_Phoenix
Install wxPython-Phoenix (Windows, use the appropriate script folder):
C:\python27\scripts\pip.exe install --upgrade --trusted-host wxpython.org --pre -f http://wxpython.org/Phoenix/snapshot-builds/ wxPython_Phoenix

I installed wxPython as part of the PsychoPy experiment builder dependencies, and had considerable trouble getting it to install properly as well initially. But this was what worked for me at the end. I use Ubuntu 16.04, python 3.5, pip3 19.0.3
pip3 install -U -f https://extras.wxpython.org/wxPython4/extras/linux/gtk3/ubuntu-16.04 wxPython --user

If you use Conda then you may easily setup the environment with wx by one line:
$ conda create -n wxenv python=3 wxPython
Solving environment: done
## Package Plan ##
environment location: /home/user/.conda/envs/wxenv
added / updated specs:
- python=3
- wxpython
The following packages will be downloaded:
package | build
---------------------------|-----------------
[...]
Proceed ([y]/n)?

You need to ensure the versions of your wxPython download matches your installed python language library.
The current downloads wxPython downloads doesn't show any libraries built against python 3. I Believe the python 3 porting project is still ongoing.
If you are not sure of what you are doing I would stick with the 32bit version on windows as there are some Python libraries (ie IIRC, MySQLdb) which don't work with 64 bit python.
So you would then need to download python2.7 for windows x86 and "wxPython3.0-win32-py27 32-bit Python 2.7"

To install wxPython GUI library correctly go to the following page (https://wxpython.org/Phoenix/snapshot-builds/), which contains snapshots builds of wxPython library (Phoenix version) depending on your os and version of Python you want to work.
Then when you downloaded the proper package for your system and python version, simply install it by using pip. In my case I've choosen that one (wxPython_Phoenix-3.0.3.dev2811+ecc4797-cp36-cp36m-win_amd64.whl):
pip install wxPython_Phoenix-3.0.3.dev2811+ecc4797-cp36-cp36m-win_amd64.whl
To check that it has been installed sucessfully on the site-packages folder for your current python environment write:
pip freeze
It's all!

Check the version of wxpython and the version of python you have in your machine.
For python 2.7 use wxPython3.0-win32-3.0.2.0-py27 package

The problem was solved in openSuse simply with
zypper in python-wxWidgets-3_0-devel
Trying pip install before, gave me a lot of trouble (missing traits, missing wx/setup.h, https://github.com/wxWidgets/Phoenix/issues/1644, error: aggregate ‘wxGLAttributes _NullGLAttributes’ has incomplete type and cannot be defined, etc.).

wxpython failed to be installed with pipenv. Pipenv is not able to find wxpython binary so it tries to build wxpython but fails.
CXXFLAGS="-I/opt/homebrew/include" pipenv install wxpython
On my macOS M1 pipenv failed to install wxPython. After a lot of searching I found a forum post which really helped me fix the problem.
Source/Credits: https://forums.wxwidgets.org/viewtopic.php?t=47953&p=203709

Install current development version with:
pip install -U https://github.com/robotframework/RIDE/archive/master.zip
(python < 3.9) Install current Beta version (2.0b1) with:
pip install psutil
pip install -U --pre robotframework-ride

Note that I tried to install wxPython with 'pip install -U wxPython' as per instruction
with no avail. Too many errors to list here. 🤨
I found a solution to the problem!!
I'm working on a 64b machine and Windows 11 operating system using VSCode.
Here is the solution using PowerShell:
Version specs:
pip 22.3.1
virtualenv 20.15.1
python 3.10.8
Create a new virtual environment in the directory where the program resides and
activate. There must be no modules installed.
virtualenv venv
venv/scripts/activate.bat
Install the following in sequence:
pip install pygame
(Not sure why pygame must be installed first, but this was
recommended and it works) 😟
pip install -U wxPython
SUCCESS!!! 🤠
These are the modules installed:
numpy 1.24.1
Pillow 9.4.0
pip 22.3.1
pygame 2.1.2
setuptools 65.4.0
six 1.16.0
wheel 0.37.1
wxPython 4.2.0
VSCode still reports wx as a missing module even when you activate the virtual
environment within. Running the code from the PS command prompt within the virtual
environment is the only working solution.
PS. I am sure there are some conflicts when trying to install wxPython within an
environment where all the other modules are installed.

How to install SciPy stack with pip and homebrew?

I'm trying to install the basic scipy stack (numpy, scipy, matplotlib, pandas, sympy, ipython, nose) into a virtualenv; currently, I'm using OSX Mountain Lion. From the installation pages for these packages, as well as various threads here and around the web, it seems that pandas, sympy, and nose can be installed easily with just pip (although some list numpy/scipy/etc. as dependencies).
However, there seems to be conflicting and kind of convoluted instructions for properly installing numpy, scipy, matplotlib, and, to a certain extent, ipython*. Installing solely with pip doesn't seem to be the proper way to install these packages; it seems that some dependencies need to be installed with homebrew, but various places list different packages to brew install before pip installing numpy/scipy/etc. Is there a comprehensive and current list of package dependencies that need to be installed with homebrew before pip installing numpy, scipy, and matplotlib?
Just as a note, I've looked at tapping homebrew/python for installing numpy, scipy, and matplotlib properly with homebrew, but I want to install into a virtualenv and I don't think I can use homebrew to do that.
Any help would be greatly appreciated; thanks in advance!
*Also, for ipython, the installation page says that pip install ipython[all] should be sufficient, but some other sources (http://www.coderstart.com/setup/python-setup.html; http://www.lowindata.com/2013/installing-scientific-python-on-mac-os-x/) seem to suggest that the qt, pyqt, and zmq packages need to be brew installed first before pip installing ipython; are the homebrew installation necessary or is it fine to just pip install according to the ipython installation page?

Answering my own question here, but hopefully this is helpful; feel free to correct if there are any mistakes. The original version is a gigantic wall of text, so I've added a tl;dr to the top with just the steps to hopefully make the process more clear.
tl;dr: In terminal/bash, go into a virtualenv (if you want to install into one) and enter these commands in order. This is tested for OSX Mountain Lion.
pip install numpy
brew install gcc
pip install scipy
brew install freetype
pip install matplotlib
pip install nose
pip install pandas
pip install sympy
pip install ipython[all]
brew install pyqt
brew install qt
brew install sip
echo "export PYTHONPATH=/usr/local/lib/python2.7/site-packages:$PYTHONPATH" >> ~/.bash_profile
source ~/.bash_profile
*Notes: brew installing pyqt might already install qt and sip; if it does, no need to install qt and sip after installing pyqt. For the second to last line, might be be more reliable to directly c/p that line into ~/.bash_profile, since it might need to be at the top of the ~/.bash_profile contents. Also, brew install pandoc is optional, but necessary for ipython notebook's nbconvert command work properly.
edit 10/13/14 [see edit at bottom]: editing PYTHONPATH in ~/.bash_profile forces virtual environments to inherit global packages; if you want to be able to make isolated environments, don't do the last two steps. Instead, assuming virtualenvwrapper is installed, edit the local postactivate and predeactivate scripts in the bin directory under the virtualenv that contains the scipy stuff.
In postactivate, enter:
export PYTHONPATH=/usr/local/lib/python2.7/site-packages:$PYTHONPATH
In predeactivate, enter:
unset PYTHONPATH
This should edit PYTHONPATH when when the virtualenv with scipy stuff is activated so that ipython qtconsole works, but should reset PYTHONPATH when the virtualenv is deactivated, so that other virtualenvs are not affected by PYTHONPATH changes.
Below is the long narrative version.
Anyway, from some trial and error after I originally posted the question, I found that the following steps work; I used the two sets of instructions that I linked above as general guides, and this was tested on OSX Mountain Lion.
After activating the virtualenv in which the packages are going to be installed, first pip install numpy; this should work as expected and numpy should be installed (note that numpy should be installed first since a lot of the other packages in the scipy stack depend on numpy).
Now, before installing scipy, several sources note that gfortran (this seems to be the most common, but I think any fortran compiler should work) needs to be installed; brew install gfortran returns an error that says that gcc now includes gfortran so the gfortran formula is deprecated. Hence, we brew install gcc (note that even though xcode command line tools, which is generally installed before homebrew, already includes gcc, its version of gcc somehow doesn't work or doesn't include gfortran). After installing gcc, pip install scipy works as expected, and scipy should be installed. Quick aside: brew install gcc installs gcc as well as a bunch of dependencies, namely cloog, gcc, gmp, isl, libmpc, mpfr. [These should all be installed into /usr/local/Cellar, which is the default install location for homebrew.]
For installing matplotlib, freetype needs to be installed first, so we brew install freetype; this should install freetype and libpng, which seems to be a freetype dependency. Afterwards, pip install matplotlib works as expected, installing matplotlib successfully. Note that matplotlib installs with mock (needed to run matplotlib test suite), pyparsing (required for mathtext support), python-dateutil (required for date axis support), six (no reason given) along with it. [These should all be installed, along with any other pip install within a virtualenv, into the site-packages directory within the virtualenv.]
Installing nose, sympy, and pandas simply require pip installing, as they don't have any dependencies that need to be brew installed. However, of these, note that at least pandas depends on numpy, so installing pandas (not sure about the others) after installing numpy is probably preferred. Also, note that pandas installs with pytz (for time zone calculations).
Installing ipython is pretty simple, but setting it up is a little more convoluted. As a heads up, ipython can be used with both a qt console and something called ipython notebook, which have various benefits. You can choose to just install ipython with pip install ipython and install optional dependencies later on as needed, but I installed all the main optional dependencies with pip install ipython[all]. This installs ipython, along with a lot of other packages dependencies (installs with backports.ssl-match-hostname (from tornado), certifi (from tornado), docutils (from sphinx), gnureadline, ipython, jinja2, markupsafe (from jinja2), numpydoc (from ipython[all]), pygments, pyzmq, sphinx, tornado). This should be a good foundation for ipython to use both the standard ipython shell, the qt console, and the ipython notebook. However, it's not fully set up if you want to use either the qt console or the notebook.
To use the qt console, the pyqt, qt, and sip packages must be brew installed, as these are dependencies that cannot be installed with pip; from experience, brew install pyqt seems to install all three packages, but individually installing the three might be a safer bet. After doing this, go into ~/.bash_profile and add the line 'export PYTHONPATH=/usr/local/lib/python2.7/site-packages:$PYTHONPATH' to it; then 'source ~/.bash_profile' in terminal to reload the shell. This should successfully allow the qt console to be launched. [I'm not totally sure why this line needs to be added, since I had already edited the PATH variable to put /usr/local/bin before /usr/bin, but perhaps qt/pyqt/sip were still trying to link themselves with the system default python instead of homebrew installed python.]
The notebook seems to work fine out of the box as far as I've seen, but there's one thing of note: in order to use nbconvert (converting the notebook to different file formats), the pandoc package must be installed, presumably with homebrew. Like qt/pyqt/sip, it can't be installed with pip which is why it wasn't installed with pip install ipython[all].
edit 10/13/14: So apparently, editing PYTHONPATH will nullify empty virtual environments, making global packages also available in a virtualenv (how to isolate virtualenv from local dist-packages?); this, for the most part, defeats the purpose of a virtualenv, assuming that you want to a fresh environment, but is necessary for ipython qtconsole to work correctly.
The fix is to edit (assuming virtualenvwrapper is installed) the local postactivate and predeactivate scripts in the bin file of your virtualenv. In postactivate, enter the line "export PYTHONPATH=/usr/local/lib/python2.7/site-packages:$PYTHONPATH; in predeactivate, enter the line "reset PYTHONPATH". Don't do the last two steps of the original sequence, or delete the line that was added to ~/bash_profile. This should make it so that the changes to PYTHONPATH are made only when the virtualenv with our installed packages is activated, so that qtconsole works, but are reset before the virtualenv deactivates, so that other environments are not affected.

I'm on OSX 10.9, but I had good luck following these instructions and get roughly the same environment that you outlined above
http://hackercodex.com/guide/python-development-environment-on-mac-osx/
Hope this helps

Installing numpy for Python 2.7 while also having Python 3.4 installed?

I have both Python 2.7 and Python 3.4 (and have to have both because for the class I'm running, students have the option of using either). One student has used Python 2.7 and numpy for their project, but when I attempt to install numpy, it installs it to 3.4. I need to install it to 2.7.
I'm using numpy 1.9 from this site, which I'm told is also 2.7-specific: http://sourceforge.net/projects/numpy/files/NumPy/
However, nonetheless it still goes to the 3.4 folder. Copying it to Python 2.7 didn't work, obviously.
How do I do this?

I recommend installing with pip.
pip install numpy
If this doesn't work on windows then download the binary from http://www.lfd.uci.edu/~gohlke/pythonlibs/ and convert it to a wheel before installing.
pip install wheel
wheel convert path/to/binary
pip install numpy_wheel
Pip is recommended because you can uninstall.
To check where you are installing to
pip -V
You may have an environmental variable path to the wrong pip.

Assuming that you are using, or at least you should use pip to install the library. You can specify the python version to be installed by changing the suffix, e.g. pip-2.7 install numpy.
pip install numpy
pip-2.7 install numpy
pip-3.4 install numpy
As an alternative, in case that you do not want to use pip is to download and install the library using setup with a similar technique.
python setup.py install
python2.7 setup.py install
python3.4 setup.py install

Your PATH isn't setup correctly.
C:> where pip
Should tell you which pip it is trying to use, and it is likely whichever one it found on your PATH first...
So, instead, you will want to run it as
C:> C:\mypython2install\pip.exe install numpy
Or, setup your path correctly. See here

Just one other note on issues like this. I had a similar problem with Python 2.7 libraries not being found, because I had miniconda installed for a Python virtual environment that was hijacking calls to python from other programs. After deleting the minconda directory in my home the problem went away and python libraries that were properly installed were found again.

Note-This answer is particularly for Windows PC which has both Python2 & Pyhton3 installed on it.
Both the versions of Python has their different directories somewhat like
"C:\Python27\" ----for python2
"C:\Python35\" ---- for python3
*(or it depends on what path you chose while installing Python**)*
pip GENERALLY exist under the directory "C:\Python**\Scripts"
there you can find exe files like:
pip.exe/pip2.exe/pip2.7.exe ----for python2
pip3.exe/pip3.5.exe ----for python3
to install packages on python2:
use
Python27\Scripts\pip2.exe install package_name
(where the 1st argument is the path of exe file, it might differ for your system)
to install packages on python3:
use
Python35\Scripts\pip3.exe install package_name
there is no need to uninstall any version of python to achieve the task.