Update 3. Get Only What You Need, and Fast.md

Author: ortizfram

Introduction to MongoDB in Python/3. Get Only What You Need, and Fast.md

@@ -61,3 +61,28 @@ full_names = [doc["firstname"] + " " + doc["surname"]  for doc in docs]
 # Print the full names
 print(full_names)
 ```
+## 🦍 Doing our share of data validation
+Each "laureates.share" value appears to be the reciprocal of a laureate's fractional share of that prize, encoded as a string. For example, a laureate "share" of "4" means that this laureate received a 
+ 
+ share of the prize. Let's check that for each prize, all the shares of all the laureates add up to 1!
+ - [x] Save a list of prizes (prizes), projecting out only the "laureates.share" values for each prize.
+ - [x] For each prize, compute the total share as follows:
+ - [x] Initialize the variable total_share to 0.
+ - [x] Iterate over the laureates for each prize, converting the "share" field of the "laureate" to float and adding the reciprocal of it (that is, 1 divided by it) to total_share.
+ ```py
+ # Save documents, projecting out laureates share
+prizes = db.prizes.find({}, ["laureates.share"])
+
+# Iterate over prizes
+for prize in prizes:
+    # Initialize total share
+    total_share = 0
+
+    # Iterate over laureates for the prize
+    for laureate in prize["laureates"]:
+        # add the share of the laureate to total_share
+        total_share += 1 / float(laureate['share'])
+
+    # Print the total share
+    print(total_share)
+    ```