Implement nearest() in list.py

lib/xmet/list.py

@@ -0,0 +1,12 @@
+def nearest(a: list, b: list) -> list:
+    """
+    For each item in list a, find the nearest value in list b, and return a
+    list of tuples with these associations.
+    """
+    ret = list()
+
+    for item in a:
+        candidates = sorted([(v, abs(item-v)) for v in b], key=lambda t: t[1])
+        ret.append((item, candidates[0][0]))
+
+    return ret