PyCharm 2021.1 Help

Cython support


PyCharm provides initial Cython support out of the box. PyCharm recognizes .pyx, .pxd, and .pxi files, and allows you to edit them. You can also compile these files into .so files using the Cython package.

Cython support

Cython files are marked with the cython icon.

Cython support includes:

Get started with Cython in PyCharm

Follow this procedure to create a .pyx file in PyCharm, edit it, and build it into a .so file using

  1. Create a new project as explained in Create a Python project.

  2. Press Ctrl+Alt+S to open the project settings and navigate to Project: <project name> | Python Interpreter.

  3. Click Add a package on the package toolbar, then type Cython in the search field of the Available Packages dialog, and click Install Package. Close the window upon successful installation and click OK in the interpreter settings.

    Installing the Cython package

  4. Now create a .pyx file. Select File | New from the main menu, then select File. Type the filename, for example, example.pyx and save the changes. The file opens in the editor.

  5. You can copy and paste the following code:

    def function (a: int, b: int) -> str: return str(a + b) function(2, 4)

    Alternatively, you can type code to see how PyCharm assists you with code completion and type checking:

    cython code completion
    cython type checking
  6. Now create the file. Select Tools | Create from the main menu. PyCharm creates a template file and opens it in the editor. You can copy and paste the following setup options:

    from setuptools import setup, Extension module = Extension ('example', sources=['example.pyx']) setup( name='cythonTest', version='1.0', author='jetbrains', ext_modules=[module] )

  7. To compile the example.pyx file, select Tools | Run Task command from the main menu. In the Enter task name type build and select the build_ext task. See Create and run for more details.

    selecting the build task
    In the Run Setup Task build_ext dialog, add the --inplace command-line agrument
    adding a command-line argument
    Once the build task successfully completes, the .so file is created.
    compilation with the build task

At this point, you can use the compiled .so file to import function:

from example import function
See Cython documentation for the complete instructions.

Last modified: 06 April 2021