Here and elsewhere

What proportion of laureates won a prize while affiliated with an institution in their country of birth? Build an aggregation pipeline to get the count of laureates who either did or did not win a prize with an affiliation country that is a substring of their country of birth -- for example, the prize affiliation country "Germany" should match the country of birth "Prussia (now Germany)".

Use $unwind stages to ensure a single prize affiliation country per pipeline document.
Filter out prize-affiliation-country values that are "empty" (null, not present, etc.) -- ensure values are "$in" the list of known values.
Produce a count of documents for each value of "affilCountrySameAsBorn" (a field we've projected for you using the $indexOfBytes operator) by adding 1 to the running sum.

Take Hint (-30 XP)

Exercise

Here and elsewhere

Instructions