Merge pull request #189 from 30-seconds/list-snippet-additions

List snippet additions

snippets/is_contained_in.md

@@ -0,0 +1,22 @@
+---
+title: is_contained_in
+tags: list,intermediate
+---
+
+Returns `True` if the elements of the first list are contained in the second one regardless of order, `False` otherwise.
+
+
+Use `count()` to check if any value in `a` has more occurences than it has in `b`, returning `False` if any such value is found, `True` otherwise.
+
+
+```py
+def is_contained_in(a, b):
+  for v in set(a):
+    if a.count(v) > b.count(v):
+      return False
+  return True
+```
+
+```py
+is_contained_in([1, 4], [2, 4, 1]) # True
+```

snippets/map_object.md

@@ -0,0 +1,21 @@
+---
+title: map_object
+tags: list,intermediate
+---
+
+Maps the values of a list to a dictionary using a function, where the key-value pairs consist of the original value as the key and the result of the function as the value.
+
+
+Use a `for` loop to iterate over the list's values, assigning the values produced by `fn` to each key of the dictionary.
+
+```py
+def map_object(itr, fn):
+  ret = {}
+  for x in itr:
+    ret[x] = fn(x)
+  return ret
+```
+
+```py
+map_object([1,2,3], lambda x: x * x) # { 1: 1, 2: 4, 3: 9 }
+```

snippets/take.md

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+---
+title: take
+tags: list,beginner
+---
+
+Returns a list with `n` elements removed from the beginning.
+
+Use slice notation to create a slice of the list with `n` elements taken from the beginning.
+
+```py
+def take(itr, n = 1):
+  return itr[:n]
+```
+
+```py
+take([1, 2, 3], 5) # [1, 2, 3]
+take([1, 2, 3], 0) # []
+```

snippets/take_right.md

@@ -0,0 +1,18 @@
+---
+title: take_right
+tags: list,beginner
+---
+
+Returns a list with `n` elements removed from the end.
+
+Use slice notation to create a slice of the list with `n` elements taken from the end.
+
+```py
+def take_right(itr, n = 1):
+  return itr[-n:]
+```
+
+```py
+take_right([1, 2, 3], 2) # [2, 3]
+take_right([1, 2, 3]) # [3]
+```