add Quantile Sketch for aggregator and postaggregator (#287)

Co-authored-by: jaimelyn.maico <jaimee07>

.pre-commit-config.yaml

@@ -3,6 +3,7 @@ repos:
     rev: 19.10b0
     hooks:
     -   id: black
+        additional_dependencies: ['click<8.1']
         language_version: python3
 
 -   repo: https://github.com/asottile/seed-isort-config

pydruid/utils/aggregators.py

@@ -25,6 +25,10 @@ def thetasketch(raw_column, isinputthetasketch=False, size=16384):
     }
 
 
+def quantilesDoublesSketch(raw_column, k=128):
+    return {"type": "quantilesDoublesSketch", "fieldName": raw_column, "k": k}
+
+
 def min(raw_metric):
     """
     .. note:: Deprecated use `longMin`, `doubleMin' instead

pydruid/utils/postaggregator.py

@@ -53,6 +53,20 @@ def rename_postagg(new_name, post_aggregator):
         ]
 
 
+class QuantilesDoublesSketchToQuantile(Postaggregator):
+    def __init__(self, name: str, field_name: str, fraction: float):
+        self.post_aggregator = {
+            "type": "quantilesDoublesSketchToQuantile",
+            "name": name,
+            "fraction": fraction,
+            "field": {
+                "fieldName": field_name,
+                "name": field_name,
+                "type": "fieldAccess",
+            },
+        }
+
+
 class Quantile(Postaggregator):
     def __init__(self, name, probability):
         Postaggregator.__init__(self, None, None, name)