Code metrics can be produced by static code analysis tools to determine complexity and non-standard practices.
Code metrics allow developers to find problematic codebase areas that may need refactoring. In addition, some metrics such as technical debt assist developers in communicating to non-technical audiences why issues with a system are occurring.
Radon is a tool for obtaining raw metrics on line counts, Cyclomatic Complexity, Halstead metrics and maintainability metrics.
Pylint contains checkers for PEP8 code style compliance, design, exceptions and many other source code analysis tools.
PyFlakes parses source files for errors and reports on them.
Pyntch is a static code analyzer that attempts to detect runtime errors. It does not perform code style checking.
Static Code Analizers for Python is an older article but goes over the basics of what Python static code analyzers do.
This Stack Overflow question on Python static code analysis tools contains comparison discussions of PyLint, PyChecker and PyFlakes.
Getting Started with Pylint goes over setting up Pylint, generating the .pylintrc file and what's in the configuration.
This /r/Python poll on what linters the community uses provides some input on using PyCharm just for its linting features as well as some other approaches.