How to properly install Python on OSX for use with OpenCV? - python

I spent the past couple of days trying to get opencv to work with my Python 2.7 install. I kept getting an error saying that opencv module was not found whenever I try "import cv".
I then decided to try installing opencv using Macports, but that didn't work.
Next, I tried Homebrew, but that didn't work either.
Eventually, I discovered I should modify the PYTHONPATH as such:
export PYTHONPATH="/usr/local/lib/python2.6/site-packages/:$PYTHONPATH"
My problem is that I didn't find /usr/local/lib/python2.*...etc
The folder simply doesn't exist
So my question is this:
How do I properly install Python on OS X Snow Leopard for it to work with opencv?
Thanks a lot,

I spent a couple days on this myself. For me, the problem was that that OpenCV installer was not finding the right python installation. It was defaulting to the MacOS-installed version despite the fact that I had upgraded python with homebrew and was using a virtualenv for python. I have collected most of my setup in a gist here:
https://gist.github.com/4150916
Use homebrew to get all the dependencies, but then download the OpenCV tarball and compile yourself being sure to specify all the python related configuration options.
Assuming a virtualenv named 'opencv'...
cd OpenCV-2.4.3/
mkdir release
cd release
cmake -D PYTHON_EXECUTABLE=$WORKON_HOME/opencv/bin/python \
-D PYTHON_PACKAGES_PATH=$WORKON_HOME/opencv/lib/python2.7/site-packages \
-D INSTALL_PYTHON_EXAMPLES=ON\
-D PYTHON_INCLUDE_DIR=/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Headers\
-D PYTHON_LIBRARY=/usr/local/Cellar/python/2.7.3/Frameworks/Python.framework/Versions/2.7/lib/libpython2.7.dylib\
..
make -j8
make install

You need to install the module using your python2.7 installation. Pointing your PYTHONPATH at stuff installed under 2.6 to run under 2.7 is a Bad Idea.
Depending on how you want to install it, do something like python2.7 setup.py or easy_install-2.7 opencv to install.
fwiw, on OS X the modules are usually installed under /System/Library/Frameworks/Python.framework/ but you should almost never need to know where anything installed in your site packages is physically located; if Python can't find them without help you've installed them wrong.

Installing OpenCV with Homebrew
brew tap homebrew/homebrew-science
brew install opencv
Setting up Python
Depending on your install location - OS X Default
cd /Library/Python/2.7/site-packages/
or - Homebrew Python
cd /usr/local/lib/python2.7
Then create the symbolic link
ln -s /usr/local/Cellar/opencv/2.4.9/lib/python2.7/site-packages/cv.py cv.py
ln -s /usr/local/Cellar/opencv/2.4.9/lib/python2.7/site-packages/cv2.so cv2.so
The above method sourced from a blog post.

I searched and tried installing opencv3 with python3 for 3 days. Some links suggest for Brew and some virtual env, some say install xcode but all failed in my case.
Dont use linux steps to instal opencv-python on Mac. Problem with Mac is Python 2.7 is already installed by Mac. On top of that installing and linking all site-packages is little problematic and we end up with errors.
I'll share what I did: easy steps to install complete package opencv3, numpy, matplotlib, notebook, spyder etc.. on Mac.
Install anaconda, it creates a directory and install everything inside that
use this link -> https://www.continuum.io/downloads
download command-line-install
After download, goto terminal and download location of anaconda.
$ bash Anaconda3-4.3.0-MacOSX-x86_64.sh
Installation will ask you to append path to .bash_profile >> say yes
Goto home directory, run .bash_profile
$ source .bash_profile
check python, should be pointing to
$ which python
$ /.../anaconda/bin/python
Last step
$ pip install opencv-pyhton
$ python
$ import cv2
if no errors, we are good to go.

Related

Unable to upgrade from Python2 to Python3 (Ubuntu 19.04)

I had python2 installed in my ubuntu (19.04) and I wanted to get it upgraded to 3.7. I installed the 3.7 but still the version showed as 2.7. but I could run python3 and go to the console and python3.7 executable was available in /usr/bin. Did try all the tricks available in internet without any luck. then I decided to delete python2.7 executable from the /usr/bin and now I cannot even run pip as it tries to find the deleted 2.7 I guess. Getting the following message.
bash: /usr/bin/pip: /usr/bin/python: bad interpreter: No such file or directory
I don't know why it's still trying to find 2.7 like ex girl friend when 3.7 is installed and available in the machine.
Did you set up a path for python 3.7 in your .bashrc file? If not, try that and that should help.
Usually a path is something like:
$ export PATH=$HOME/Nek5000/bin:$PATH
First, run an update to make sure that there aren’t newer versions of the required packages.
sudo apt update --fix-missing
Next, you can try forcing Apt to look for and correct any missing dependencies or broken packages. This will actually install any missing packages and repair existing installs.
sudo apt install -f
(Source)
Also, always remember - never install directly in global environment. You should always create a local environment first(i recommend venv) as there are very high chances you can break something globally.
You can create a local environment by -
python3 -m venv tutorial-env
where tutorial-env is the name of your environment.
To activate this environment, you should run
source tutorial-tutorial-env/bin/activate

How to move all modules to new version of Python (from 3.6 to 3.7)

I just upgraded to python 3.7 and I realized that all my modules stuck with the previous version. Even Django is not recognised anymore. How can I do to transfer everything to the new version? I am a little lost right now, don't even know where the new version has been installed.
Edit:
When I do $ which python3.6 the terminal tells me it doesn't exist, but I have a python3.6 directory in /usr/local/lib/, where all modules are installed.
In the same directory /usr/local/lib/ I also have a python3.7 directory with some modules installed but many are missing. However when I search for the file python3.7 in my finder it doesn't appear. when I do $ which python3.7 the path is /usr/local/bin so not the same path as the directory.
Anyone sees what happened and knows how I can transfer all modules to python3.7?
Even if the old python version has been removed, it is possible to use the pip of the current python version with the --path option to list all the modules installed in the previous version.
For example, migrating all my user installed python modules from 3.7 to 3.8
pip freeze --path ~/.local/lib/python3.7/site-packages > requirements.txt
pip install --user -r requirements.txt
Incidentally, I always use pip install with --user and leave the system wide installations to the package manager of my linux distro.
It is safer to re-install all packages due to possible compatibility issues:
pip3.6 list | awk '{print $1}' | xargs -I{} pip3.7 install {}
in older version of Python --run the command
pip freeze > requirements.txt
download and install newer version on python.. change the PATH variable to the new version
and run the command
pip install -r requirements.txt
I'm not sure about all modules...but if you want to install a module specifically in python3.7, try this:
python3.7 -m pip install *module_name*
In some cases, we don't have the opportunity to pip freeze in old version--because I've already updated and old version have been purged! There are some measures I've taken to recover some of the packages but I'm NOT sure every package would work with this fix.(e.g. the packages built with wheels)
mv /your/path/to/python3.{6,7}/site-packages/
If the case is packages installed outside venv (in /usr/local/ or ~/.local), reinstall pip with get-pip.py, just to be safe.
If you are recovering a virtualenv. Activate your virtualenv and use my script
Most of your packages should work by now. If anything malfunctions, pip reinstall would works. If you still want it 100% works, pip freeze now.😉
I have an alternative
(Not sure if works outside Windows 10)
I'm currently migrating from 3.7 to 3.8 and the way I found to re-install my previous libraries was by using a script I had that updates all packages via pip install. (Assuming you installed your new Python version as your main version) This checks for all the packages I had and updates/install them in the new Python version.
Note: I prefer to run the script from the command line
Use the file explorer to go to the folder where you have the script;
Click on the path box, write "cmd" and press enter to open a command line from the folder where you are;
Write "python name_of_your_script.py" and press enter to run the command.
The script (adapted from this solution):
import pkg_resources
from subprocess import call
packages = [dist.project_name for dist in pkg_resources.working_set]
[call("pip install " + name + " --upgrade") for name in packages]
I faced a similar problem, now that I upgraded from python 3.7 to python 3.8 (new)
I installed Python 3.8, but the system kept the python37 subfolder with the already installed packages(...\Python37-32\Lib\site-packages) even with the Pyhton38 subfolder created, with the new python.exe.
Usually, it's possible to keep on using the old libraries on your new Python version, because the existent libraries installation folder are already registered in your local computer system path (*).
Even though, I've had problems to use some libraries (some worked in Jupyter Notebook but not in Spyder). I tried the alternatives others proposed to migrate libraries but it did not worked (maybe I did not
So I used brutal force solution.. Not elegant at all, but it worked:
remove the OLD python version folders from the system path or even remove the folder itself for good..
Folders: C:\Users\USERNAME\AppData\Roaming\Python\Python37
C:\Users\USERNAME\AppData\Local\Programs\Python\Python37
Reinstall the packages you need, preferably via Anaconda prompt.
python -mpip install library_name
OR
pip install --user --force-reinstall package_name
OR
pip install --user --force-reinstall package_name == specify_package_version
The libraries will be installed at c:\users\USERNAME\anaconda3\lib\site-packages and recognized by your new python version.
(*) to add the folder to the PATH: System properties --> environment variables --> click "Path"--> edit --> add folder name)

Debian 8: Installed Python 2.7.13 But No Pip; Packages Install to Wrong Path

I am running Debain 8 Jessie and have installed python 2.7.13 into /usr/local/bin.
I do not have a new pip installed, I am still using the pip located at /usr/bin/. Any time I install a package using pip, they are installed to the dist-packages location of my new python install:
/usr/local/lib/python2.7/dist-packages
Question
How do I get my pip installs to permanently install in /usr/lib/python2.7/dist-packages? What is even weirder, is that although these packages are installing to a location seemingly setup by my new install, I cannot import whatever I download when I am using python2.7.13 via /usr/local/bin/python.
PATH
/usr/bin:/usr/local/bin:/usr/local/sbin:/usr/sbin:/sbin:/bin:
Better Yet
How do I just get my python2.7.13 install to see the installed packages from pip?
Run this:
import sys
for p in sys.path:
print p # or print(p) if you prefer.
Look for /usr/lib/python2.7
if not you'll want to
export PYTHONPATH=/usr/local/lib/python2.7:/usr/lib/python2.7
in .bashrc or in a special (host-wide) script in /etc/profile.d/
If /usr/lib/python2.7/
Depending on the difference between your "stock" version and 2.7.13, you might not want to put stuff in /usr/lib/python2.7. On my system I'd really want to avoid any cross contamination, but that's something I'm a bit picky about.

How to update macOS Python packages

I've been getting the following notice every time I fire up Terminal recently:
/usr/local/lib/python3.5/site-packages/powerline/bindings/zsh/powerline.zsh:200: /usr/local/bin/powerline-config: bad interpreter: /usr/local/opt/python3/bin/python3.5: no such file or directory
/usr/local/lib/python3.5/site-packages/powerline/bindings/zsh/powerline.zsh:204: /usr/local/bin/powerline-config: bad interpreter: /usr/local/opt/python3/bin/python3.5: no such file or directory'
I posted this to the powerline GitHub page as an issue and was advised that I have probably updated my Python version on macOS without me knowing (through homebrew or perhaps through a system update, since I'm a macOS Beta user).
Is there a way to update Python packages en-masse in macOS as in Gentoo, as pointed out in the linked GitHub issue? The dev mentioned that there is a python-updater script in Gentoo that is used to update packages after updating Python, but no such script exists for macOS.
OS: macOS 10.12.3 Beta
Any help would be appreciated!
-- paanvaannd
I think the diagnosis from the powerline GitHub page is correct: you updated Python 3.5 to 3.6 via Homebrew, so things expecting the 3.5 interpreter are broken. I've done this a couple of times.
The best way I've found to keep things sane is to store a list of the installed packages, remove them, update Python via Homebrew, and then reinstall the list of packages. In the shell this would be:
$ pip3 list | cut -d " " -f 1 > package-list.txt # Store package names without versions
$ pip3 uninstall -y $(cat package-list.txt) # Cannot use redirection
$ brew update && brew upgrade python3
$ pip3 install $(cat package-list.txt)
This isn't very helpful for you now, because you've already upgraded with out keeping this list. One option is to roll back your Python installation via Homebrew. If you've not yet done brew cleanup, you can do brew switch python3 3.5.x (where x is the latest version you had). After this, you can do the procedure above, swapping brew upgrade python3 with brew switch python3 3.6.0.
If you've cleaned up the previous installation, you can try to reinstall it, using this answer, and then do the above.
If both those fail, you can just manually re-install your packages. Look at what's in /usr/local/lib/python3.5/site-packages/ for a list of the packages you had installed via Pip, and install them manually. The best thing is to pick one with lots of dependencies, so that you install many packages at once.

Problem with virtualenv in Mac OS X

I've installed virtualenv via pip and get this error after creating a new environment:
selenium:~ auser$ virtualenv new
New python executable in new/bin/python
ERROR: The executable new/bin/python is not functioning
ERROR: It thinks sys.prefix is u'/System/Library/Frameworks/Python.framework/ Versions/2.6' (should be '/Users/user/new')
ERROR: virtualenv is not compatible with this system or executable
In my environment:
PYTHONPATH=/System/Library/Frameworks/Python.framework/Versions/2.6/lib/python2.6/site-packages
PATH=/System/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/Library/Frameworks/Python.framework/Versions/2.6/bin:/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin:/usr/X11/bin
How can I repair this?
Thanks.
Just in case there's someone still seeking for the answer.
I ran into this same problem just today and realized since I already have Anaconda installed, I should not have used pip install virtualenv to install virtual environment as this would give me the error message when trying to initiate it later. Instead, I tried conda install virtualenv then entered virtualenv env_mysite and problem solved.
Like #RyanWilcox mentioned, you might be inadvertently pointing virtualenv to the wrong Python installation. Virtualenv comes with a -p flag to let you specify which interpreter to use.
In my case,
virtualenv test_env
threw the same error as yours, while
virtualenv -p python test_env
worked perfectly.
If you call virtualenv -h, the documentation for the -p flag will tell you which python it thinks it should be using; if it looks wonky, try passing -p python. For reference, I'm on virtualenv 1.11.6.
In case anyone in the future runs into this problem - this is caused by your default Python distribution being conda. Conda has it's own virtual env set up process but if you have the conda distribution of python and still wish to use virtualenv here's how:
Find the other python distribution on your machine: ls -ls /usr/bin/python*
Take note of the availble python version that is not conda and run the code below (note for python 3 and above you have to upgrade virtualenv first): virtualenv -p python2.7(or your python version) flaskapp
I've run across this problem myself. I wrote down the instructions in a README, which I have pasted below....
I have found there are two things that work:
Make sure you're running the latest virtualenv (1.5.1, of this writting)
If you're using a non system Python as your standard Python (which python to check) Forcefully use the System supplied one.
Instead of virtualenv thing use /usr/bin/python2.6 PATH/TO/VIRTUALENV thing (or whatever which
python returned to you - this is what it did for me when I ran into this issue)
I had the same problem and as I see it now, it was caused by a messy Python installation. I have OS X installed for over a year since I bought a new laptop and I have already installed and reinstalled Python for several times using different sources (official binaries, homebrew, official binaries + hand-made adjustments as described here). Don't ask me why I did that, I'm just a miserable newbie believing everything will fix itself after being re-installed.
So, I had a number of different Pythons installed here and there as well as many hardlinks pointing at them inconsistently. Eventually I got sick of all of them and reinstalled OS X carefully cleaned the system from all the Pythons I found using find utility. Also, I have unlinked all the links pointing to whatever Python from everywhere. Then I've installed a fresh Python using homebrew, installed virtualenv and everything works as a charm now.
So, my recipe is:
sudo find / -iname "python*" > python.log
Then analyze this file, remove and unlink everything related to the version of Python you need, reinstall it (I did it with homebrew, maybe official installation will also work) and enjoy. Make sure you unlink everything python-related from /usr/bin and /usr/local/bin as well as remove all the instances of Frameworks/Python.framework/Versions/<Your.Version> in /Library and /System/Library.
It may be a dirty hack, but it worked for me. I prefer not to keep any system-wide Python libraries except pip and virtualenv and create virtual environments for all of my projects, so I do not care about removing the important libraries. If you don't want to remove everything, still try to understand whether your Pythons are, what links point to them and from where. Then think what may cause the problem and fix it.
I ran into a variation of this "not functioning" error.
I was trying to create an environment in a folder that included the path ".../Programming/Developing..." which is actually "/Users/eric/Documents/Programming:Developing/"
and got this error:
ImportError: No module named site
ERROR: The executable env/bin/python2.7 is not functioning
ERROR: It thinks sys.prefix is u'/Users/eric/Documents/Programming:Developing/heroku' (should be u'/Users/eric/Documents/Programming:Developing/heroku/env')
ERROR: virtualenv is not compatible with this system or executable
I tried the same in a different folder and it worked fine, no errors and env/bin has what I expect (activate, etc.).
I got the same problem and I found that it happens when you do not specify the python executable name properly. So for python 2x, for example:
virtualenv --system-site-packages -p python mysite
But for python 3.6 you need to specify the executable name like python3.6
virtualenv --system-site-packages -p python3.6 mysite
On on OSX 10.6.8 leopard, after having "upgraded" to Lion, then downgrading again (ouch - AVOID!), I went through the Wolf Paulus method a few months ago, completely ignorant of python. Deleted python 2.7 altogether and "replaced" it with 3.something. My FTP program stopped working (Fetch) and who knows what else relies on Python 2.7. So at that point I downloaded the latest version of 2.7 from python.org and it's installer got me up and running - until i tried to use virtualenv.
What seems to have worked for me this time was totally deleting Python 2.7 with this code:
sudo rm -R /System/Library/Frameworks/Python.framework/Versions/2.7
removing all the links with this code:
sudo rm /usr/bin/pydoc
sudo rm /usr/bin/python
sudo rm /usr/bin/pythonw
sudo rm /usr/bin/python-config
I had tried to install python with homebrew, but apparently it will not work unless all of XTools is installed, which I have been avoiding, since the version of XTools compatible with 10.6 is ancient and 4GB and mostly all I need is GCC, the compiler, which you can get here.
So I just installed with the latest download from python.org.
Then had to reinstall easy_install, pip, virtualenv.
Definitely wondering when it will be time for a new laptop, but there's a lot to be said for buying fewer pieces of hardware (slave labor, unethical mining, etc).
The above solutions failed for me, but the following worked:
python3 -m venv --without-pip <ENVIRONMENT_NAME>
. <ENVIRONMENT_NAME>/bin/activate
curl https://bootstrap.pypa.io/get-pip.py | python
deactivate
It's hacky, but yes, the core problem really did just seem to be pip.
I did the following steps to get virtualenv working :
Update virtualenv as follows :
==> sudo pip install --upgrade virtualenv
Initialize python3 virtualenv :
==> virtualenv -p python3 venv
I had this same issue, and I can confirm that the problem was with an outdated virtualenv.py file.
It was not necessary to do a whole install --upgrade.
Replacing the virtualenv.py file with the most recent version sufficed.
I also had this problem, and I tried the following method which worked for me:
conda install virtualenv
virtualenv --system-site-packages /anaconda/envs/tensorflow (here envs keeps all the virtual environments made by user)
source /anaconda/envs/tensorflow/bin/activate
Hope it's helpful.
I had this same issue when trying to install py2.7 on a newer system. The root issue was that virtualenv was part of py3.7 and thus was not compatible:
$ virtualenv -p python2.7 env
Running virtualenv with interpreter /usr/local/bin/python2.7
New python executable in /Users/blah/env/bin/python
ERROR: The executable /Users/blah/env/bin/python is not functioning
ERROR: It thinks sys.prefix is u'/Library/Frameworks/Python.framework/Versions/2.7' (should be u'/Users/blah/env')
ERROR: virtualenv is not compatible with this system or executable
$ which virtualenv
/Library/Frameworks/Python.framework/Versions/3.7/bin/virtualenv
# install proper version of virtualenv
$ pip2.7 install virtualenv
$ /Library/Frameworks/Python.framework/Versions/2.7/bin/virtualenv -p python2.7 env
$ . ./env/bin/activate
(env) $
Open terminal and type /Library/Frameworks/Python.framework/Versions/
then type ls /Library/Frameworks/Python.framework/Versions/2.7/bin/
if you are using Python2(or any other else).
Edit ~/.bash_profile and add the following line:
export PATH=$PATH:/Library/Frameworks/Python.framework/Versions/2.7/bin/
cat ~/.bash_profile
In my case the content of ~/.bash_profile is as follows:
export PATH=$PATH:/Library/Frameworks/Python.framework/Versions/2.7/bin/
Now the virtualenv command should work.
If you continue to have trouble with virtualenv, you might try pythonbrew, instead. It's an alternate solution to the same problem. It works more like Ruby's rvm: It builds and creates an entire instance of Python, under $HOME/.pythonbrew, and then sets up some bash functions that allow you to switch easily between versions. Where virtualenv shadows the system version of Python, using symbolic links as part of its solution, pythonbrew builds entirely self-contained installations of Python.
I used virtualenv for years. It's a decent solution, but I've switched to pythonbrew lately. Having completely self-contained Python instances means that installing a new one takes awhile (since pythonbrew actually compiles Python from scratch), but the self-contained nature of each installation appeals to me. And disk is cheap.

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