Day 4 notebook and README links

README.md

@@ -32,3 +32,21 @@ $ pip install -e .
 - [PyData Sphinx Theme](https://pydata-sphinx-theme.readthedocs.io/en/stable/)
 - [Sphinx AutoAPI](https://sphinx-autoapi.readthedocs.io/en/latest/)
 - Find the refactoring Give It A Try in `files/convert_mass.py`
+
+# Day 4 Resourecs
+- The `[Day 4 Notebook](files/Day4.ipynb) is in `files/Day4.ipynb`.
+- [Arrays and Lists](https://blog.dillerdigital.com/arrays-and-lists/) from the Diller Digital Blog
+- [Cython](https://cython.org/) - tool for building C extensions in Python.  Particularly good for seamlessly handing off Numpy `ndarray`s to C-array code.  Tim and Corran's former coworker Kurt Smith literally [wrote the book](https://www.oreilly.com/library/view/cython/9781491901731/) on Cython.
+- [`ctypes`](https://docs.python.org/3/library/ctypes.html) - a lower level tool for extending Python with C.
+- [Tim's favorite logging setup](https://github.com/timdiller/favorite_logging_setup) on Github.
+- [`line_profiler`](https://kernprof.readthedocs.io/en/latest/#line-profiler-basic-usage) written by Tim and Corran's former coworker Robert Kern (hence the name `kernprof` for the command line tool).  Summary of usage:
+  ```
+  > pip install line_profiler
+  # add `from line_profiler import profile` to module to be profiled
+  # decorate functions to be profiled with `@profile`
+  > kernprof -l module_to_profile.py
+  Wrote profile results to 'module_to_profile.py.lprof'
+  Inspect results with:
+  python -m line_profiler -rmt module_to_profile.py.lprof
+  > python -m line_profiler -rmt module_to_profile.py.lprof
+  ```