PyCharm provides initial Cython support out-of-the-box. PyCharm recognizes .pyx, .pxd, and .pxi files, and allows you to edit them.
However, if you want to compile and run .pyx files, make sure that the following prerequisites are met:
Cython is downloaded and installed on your computer.
C compiler is downloaded and installed on your computer.
Cython files are marked with icon.
Cython support includes:
Code inspections. Almost all Python code inspections work for Cython.
Advanced facilities to search through the source code, in particular, finding usages.
Compiling Cython modules:
Compilation is done using external tools. The preferred build systems (Makefile, setup.py, and so on) should be configured as external tools.
C compiler should be downloaded and installed on your computer.