Add Sort Normalized Version Of Data as a Python TIL

python/sort-normalized-version-of-data.md

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+# Sort Normalized Version Of Data
+
+Let's say I have a list of names that I want to sort. However, because of
+inconsistency in how the data was entered, sometimes those names are capitalized
+and other times they are not. Using
+[`methodcaller`](https://docs.python.org/3/library/operator.html#operator.methodcaller),
+I can normalize the sorting `key` used when comparing list items.
+
+First, let's look at calling `sorted` with the list and no `key`:
+
+```python
+>>> sorted(["butler", "Jemisin", "le guin", "Erdrich"])
+['Erdrich', 'Jemisin', 'butler', 'le guin']
+```
+
+`butler` which starts with a `b` gets moved to the 3rd position because it is
+lowercase.
+
+To sort this list using a normalized comparison, we will use `methodcaller` to
+create a callable out of `lower` which is then passed as the sort `key`:
+
+```python
+>>> from operator import methodcaller
+>>> sorted(["butler", "Jemisin", "le guin", "Erdrich"], key=methodcaller("lower"))
+['butler', 'Erdrich', 'Jemisin', 'le guin']
+```
+
+That's the sort order I was originally hoping for.
+
+What `methodcaller` is doing is creating a callable function that will invoke
+`lower` with each string instance as the target. Conceptually similar to
+`"Erdrich".lower()` or even `getattr("Erdrich", "lower")()` (notice this needs
+to be immediately invoked).