Catalina Python3

Posted By admin  On 16.09.21

Mac OS X comes with Python 2.7 out of the box.

You do not need to install or configure anything else to use Python 2. Theseinstructions document the installation of Python 3.

Install OpenCV 4 with Python 3 on macOS Catalina Posted on October 21, 2019 by Paul. Updated 11 February 2020. In this article, I will show you how to install OpenCV 4 with Python 3 on macOS Catalina. There is also a video version of this tutorial. Pyemd fails to install on python 3.7 environment on Mac OS X Catalina (version 10.15 beta). Similar to issue I am using virtualenv with python 3.7.1.

The version of Python that ships with OS X is great for learning, but it’s notgood for development. The version shipped with OS X may be out of date from theofficial current Python release,which is considered the stable production version.

Catalina Python3

Doing it Right¶

Let’s install a real version of Python.

Before installing Python, you’ll need to install GCC. GCC can be obtainedby downloading Xcode, the smallerCommand Line Tools (must have anApple account) or the even smaller OSX-GCC-Installerpackage.

Note

Macos Catalina Python3.8

If you already have Xcode installed, do not install OSX-GCC-Installer.In combination, the software can cause issues that are difficult todiagnose.

Note

If you perform a fresh install of Xcode, you will also need to add thecommandline tools by running xcode-select--install on the terminal.

While OS X comes with a large number of Unix utilities, those familiar withLinux systems will notice one key component missing: a package manager.Homebrew fills this void.

To install Homebrew, open Terminal oryour favorite OS X terminal emulator and run

The script will explain what changes it will make and prompt you before theinstallation begins.Once you’ve installed Homebrew, insert the Homebrew directory at the topof your PATH environment variable. You can do this by adding the followingline at the bottom of your ~/.profile file

If you have OS X 10.12 (Sierra) or older use this line instead

Now, we can install Python 3:

This will take a minute or two.

Pip¶

Homebrew installs pip pointing to the Homebrew’d Python 3 for you.

Working with Python 3¶

At this point, you have the system Python 2.7 available, potentially theHomebrew version of Python 2 installed, and the Homebrewversion of Python 3 as well.

will launch the Homebrew-installed Python 3 interpreter.

will launch the Homebrew-installed Python 2 interpreter (if any).

will launch the Homebrew-installed Python 3 interpreter.

If the Homebrew version of Python 2 is installed then pip2 will point to Python 2.If the Homebrew version of Python 3 is installed then pip will point to Python 3.

The rest of the guide will assume that python references Python 3.

Pipenv & Virtual Environments¶

The next step is to install Pipenv, so you can install dependencies and manage virtual environments.

A Virtual Environment is a tool to keep the dependencies required by different projectsin separate places, by creating virtual Python environments for them. It solves the“Project X depends on version 1.x but, Project Y needs 4.x” dilemma, and keepsyour global site-packages directory clean and manageable.

For example, you can work on a project which requires Django 1.10 while alsomaintaining a project which requires Django 1.8.

So, onward! To the Pipenv & Virtual Environments docs!

This page is a remixed version of another guide,which is available under the same license.

Posted on October 21, 2019 by Paul

Updated 11 February 2020

In this article, I will show you how to install OpenCV 4 with Python 3 on macOS Catalina.

There is also a video version of this tutorial:

MacOS comes by default with Python 2.7 which, at this point, receives only bug fixes and will be EOL by 2020. Python 3.x is the future and it is supported by all major Python libraries. In this tutorial, we’ll use the Python 3.8.

Start by installing the Command Line Tools for macOS. Please note, that you will need the Command Line Tools even if you’ve already installed Xcode. Open a Terminal and write:

Once the Command Line Tools are installed, we can install Python.

The official installer of Python is a pkg file that will start a GUI installer which will guide you through the installation. You can also check the video version of this tutorial if you want to see how I did it.

Uninstall Python3 Catalina

As a side note, you can have multiple Python 3 versions installed on your macOS machine. If this is the case, you can select which version you want to use by specifying the version number, e.g.:

or:

After the above, you can invoke Python 3.8 using the python3.8 command. python3 will also invoke the latest installer version of Python 3. This is what I see if I run python3.8 on my machine:

Next, let’s follow best practices and create a new Python environment in which we can install NumPy and OpenCV:

At this point, your prompt should indicate that you are using the work environment. You can read more about Python environments in the documentation.

Once an environment is activated, all the install commands will apply only to the current environment. By default, if you close your Terminal, the environment is deactivated. If you want to be able to use it, use the source work/bin/activate command.

Catalina Python 3

Catalina Python3

We can install NumPy and OpenCV with:

Please note that the above will install the slightly older OpenCV 4.1, latest binary version doesn’t seem to work on macOS Catalina!

As a side note, when you are in a new environment you can use python to invoke the Python interpreter, no need to use the version number.

At this point, you should have OpenCV 4 and Python installed on your Mac. We can write a small test program that will print the OpenCV version, load an image from the disk, convert the image to gray and show the result. Start by downloading the next image:

Save it as clouds.jpg. In the same folder where you’ve saved the above image, create a new file demo.py and write the next code:

Run the code with:

Mac Catalina Python3 Default

Catalina Python3

Catalina Python3 インストール

(You can close the two windows by pressing ESC!)

You should see something like in the next figure. By default, the last image (the gray one) will be over the first one. You need to move the window in order to see both images:

Catalina Python 3 Download

If you want to learn more about OpenCV and Python I would recommend reading OpenCV with Python Blueprints by M. Beyeler:

or, OpenCV with Python By Example by G. Garrido and P. Joshi: