Tidy & polish Norway meetup notes

src/clojure_norway/meetup_2025_12.clj

@@ -1,5 +1,5 @@
 ^{:kindly/hide-code true
-  :clay {:title "# Noway Clojure Meetup Dec. 2025: Data analysis"
+  :clay {:title "A featherweight introduction to datasets and plots for the Norwegian Clojurians"
          :quarto {:author [:com.github/teodorlu :daslu]
                   :description "Meetup notes"
                   :category :clojure
@@ -12,28 +12,63 @@
             [scicloj.kindly.v4.kind :as kind]
             [scicloj.metamorph.ml.rdatasets :as rdatasets]
             [scicloj.tableplot.v1.plotly :as plotly]
-            [tablecloth.api :as tc]))
+            [tablecloth.api :as tc]
+            [tech.v3.dataset :as ds]))
 
-;; - Has GDP per capita improved since 1950?
-;; - Are trends different per continent?
+;; This document serves as a featherweight introduction to Tablecloth datasets
+;; and Tableplot plotting for programmers familiar with Clojure, but unfamiliar
+;; with Data Science.
+
+;; We will pick a real problem for our learning endevaours:
+;;
+;; > Has GDP per capita improved since 1950?
+;;
+;; This is a big question, and we will only provide the beginning of an answer.
 
 (def ds
   (-> (rdatasets/gapminder-gapminder)
       (tc/order-by :year)))
 
+;; Our source data is the [gapminder dataset](https://www.gapminder.org/data/).
+;; Luckily for us, the gapminder dataset is available as clean Clojure data!
+;;
+;; Let's have a peek:
+
+(ds/head ds)
+(count (ds/rows ds))
+
+;; We observe,
+;; - each country+year is it's own row
+;; - there are lots of rows
+
+;; To see better, let's plot each country along its own line.
+
 (-> ds
-    (tc/order-by :year)
     (plotly/layer-line {:=x :year
                         :=y :gdp-percap
                         :=color :country}))
 
+;; We expected GDP per capita to *increase*.
+;; But there's a sharply decreasing line!
+;; Hovering our cursor over the line, we see that it's Kuwait.
+;;
+;; Let's investigate.
+;; First, let's narrow our focus to only Kuwait.
+
 (def kuwait? (comp #{"Kuwait"} :country))
 
 (def ds-kuwait
   (-> ds
       (tc/order-by [:country :year])
       (tc/select-rows kuwait?)))
 
+;; First, we repeat GDP per capita per year, only for Kuwait.
+
+(-> ds-kuwait
+    (plotly/layer-line {:=x :year
+                        :=y :gdp-percap
+                        }))
+
 ;; Why does gdp per capita decrease in Kuwait?
 
 (-> ds-kuwait