Add min_by and max_by snippets

snippets/max_by.md

@@ -0,0 +1,17 @@
+---
+title: max_by
+tags: math,list,function,beginner
+---
+
+Returns the maximum value of a list, after mapping each element to a value using the provided function.
+
+use `map()` with `fn` to map each element to a value using the provided function, convert to a `list` and use `max()` to return the maximum value.
+
+```py
+def max_by(lst, fn):
+  return max(list(map(fn,lst)))
+```
+
+```py
+max_by([{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }], lambda v : v['n']) # 8
+```

snippets/min_by.md

@@ -0,0 +1,17 @@
+---
+title: min_by
+tags: math,list,function,beginner
+---
+
+Returns the minimum value of a list, after mapping each element to a value using the provided function.
+
+use `map()` with `fn` to map each element to a value using the provided function, convert to a `list` and use `min()` to return the minimum value.
+
+```py
+def min_by(lst, fn):
+  return min(list(map(fn,lst)))
+```
+
+```py
+min_by([{ 'n': 4 }, { 'n': 2 }, { 'n': 8 }, { 'n': 6 }], lambda v : v['n']) # 2
+```