Add map_values snippet

snippets/map_values.md

@@ -0,0 +1,25 @@
+---
+title: map_values
+tags: object,function,intermediate
+---
+
+Creates an object with the same keys as the provided object and values generated by running the provided function for each value.
+
+Use `dict.keys()` to iterate over the object's keys, assigning the values produced by `fn` to each key of a new object.
+
+```py
+def map_values(obj, fn):
+  ret = {}
+  for key in obj.keys():
+    ret[key] = fn(obj[key])
+  return ret
+```
+
+```py
+users = {
+  'fred': { 'user': 'fred', 'age': 40 },
+  'pebbles': { 'user': 'pebbles', 'age': 1 }
+}
+
+map_values(users, lambda u : u['age']) # {'fred': 40, 'pebbles': 1}
+```