Clojure adding up keys in map [closed] - clojure

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Hey guys I'm playing around with a personal project I'm making as I'm new to clojure, its measuring football players performance.
This is the a partial example of the data I am using
:Performance 2019, :Day 1, :CR7 43, :Messi -2,
:Performance 2019, :Day 2, :CR7 12, :Messi 6,
:Performance 2019, :Day 3, :CR7 -11, :Messi 4,
:Performance 2019, :Day 4, :CR7 4, :Messi 32,
:Performance 2019, :Day 5, :CR7 21, :Messi -48,
The years in the data that I'm using go back to around 2010 and the days go upto 31, It would have been to much to put here so I included a sample. The numbers next to the players CR7 and Messi are personal performance indicators that I have given them. There's less players for now but over time I will add more.
Ive stored the data in a zipmap like so
(zipmap [:Performance :Day :CR7 :Messi
My question is how would you add up all the ratings for each player from the 31 days and work out their highest performing year, bare in mind the years go back to 2010-2020

Answer 1

You can make the problem more tractable by re-shaping the data to avoid mixing program-logic keys (:Performance and :Day) with data ("CR7" and "Messi" for now).
For example, you could state the database as a list of assertions:
[{:performance 2019 :day 3 :player "CR7" :rating -11}
{:performance 2019 :day 3 :player "Messi" :rating 4}
...]
Conveniently, you could source that data from a CSV file, making it easy to add facts about more players without revising the column structure of the data.
Computationally, you face two challenges. 1) For each player, for each year, sum the ratings. 2) For each player, harvest the year of the highest rating.
The result of challenge No.1 is probably a map of player to (map of year to sum of ratings). Like this:
{"CR7" {2018 44, 2019 73, 2020 81}
"Messi" {2018 32, 2019 11, 2020 6}}
To get there, you need to transform a list (of assertions) to a single thing (a map of player to years' ratings). A Clojure standard-library function that transforms a list to a single thing is reduce. With each input record (one year, one day, one player, one rating) you update the reduction by adding the rating to one counter. The standard-library function update-in will be just the ticket.
For challenge No.2, you want the year with the highest rating. The standard-library function max-key could be helpful there.