From cdf9a7d7ae2a48d9f435edc522e2ac502e07ac31 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Tue, 31 Dec 2024 18:26:12 +0100
Subject: [PATCH] Compute article rankings by link degrees

---
 brood/src/commands/stats.rs         |  3 ++
 brood/src/commands/stats/degrees.rs | 84 +++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 brood/src/commands/stats/degrees.rs

diff --git a/brood/src/commands/stats.rs b/brood/src/commands/stats.rs
index 5ee1272..760cec6 100644
--- a/brood/src/commands/stats.rs
+++ b/brood/src/commands/stats.rs
@@ -1,3 +1,4 @@
+mod degrees;
 mod redirects;
 
 use std::io;
@@ -8,6 +9,7 @@ use crate::data::Data;
 
 #[derive(Debug, clap::Parser)]
 enum Command {
+    Degrees(degrees::Cmd),
     Redirects(redirects::Cmd),
 }
 
@@ -22,6 +24,7 @@ impl Cmd {
     pub fn run(self, data: Data) -> io::Result<()> {
         if let Some(cmd) = self.command {
             return match cmd {
+                Command::Degrees(cmd) => cmd.run(data),
                 Command::Redirects(cmd) => cmd.run(data),
             };
         }
diff --git a/brood/src/commands/stats/degrees.rs b/brood/src/commands/stats/degrees.rs
new file mode 100644
index 0000000..e73c0cf
--- /dev/null
+++ b/brood/src/commands/stats/degrees.rs
@@ -0,0 +1,84 @@
+use std::{cmp::Reverse, io};
+
+use crate::{
+    algo,
+    data::{Data, Page},
+    util,
+};
+
+/// Show stats on article in- and out-degrees.
+#[derive(Debug, clap::Parser)]
+pub struct Cmd {
+    #[arg(long, short, default_value_t = 5)]
+    top: usize,
+}
+
+impl Cmd {
+    pub fn run(self, mut data: Data) -> io::Result<()> {
+        println!(">> Outdegree");
+        println!("> Counting links");
+        let mut outdegree = vec![usize::MAX; data.pages.len()];
+        for node in data.graph.nodes() {
+            outdegree[node.usize()] = data.graph.edge_range(node).len();
+        }
+
+        println!(">> Indegree");
+        println!("> Inverting edges");
+        algo::invert(&mut data);
+        let mut indegree = vec![usize::MAX; data.pages.len()];
+        println!("> Counting links");
+        for node in data.graph.nodes() {
+            indegree[node.usize()] = data.graph.edge_range(node).len();
+        }
+
+        let mut by_degrees = data
+            .pages
+            .iter()
+            .zip(outdegree)
+            .zip(indegree)
+            .map(|((p, od), id)| (p, od, id))
+            .collect::<Vec<_>>();
+
+        println!();
+        println!("Most outlinks");
+        println!("¯¯¯¯¯¯¯¯¯¯¯¯¯");
+
+        by_degrees.sort_by_key(|(_, od, _)| Reverse(*od));
+        self.print_links(&by_degrees);
+
+        println!();
+        println!("Most inlinks");
+        println!("¯¯¯¯¯¯¯¯¯¯¯¯");
+
+        by_degrees.sort_by_key(|(_, _, id)| Reverse(*id));
+        self.print_links(&by_degrees);
+
+        by_degrees.retain(|(_, od, id)| *od > 0 && *id > 0);
+
+        println!();
+        println!("Most outlinks per non-zero inlink");
+        println!("¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯");
+
+        by_degrees.sort_by(|(_, od1, id1), (_, od2, id2)| {
+            let r1 = *od1 as f32 / *id1 as f32;
+            let r2 = *od2 as f32 / *id2 as f32;
+            r2.total_cmp(&r1) // Reverse order so max values are at beginnibg
+        });
+        self.print_links(&by_degrees);
+
+        println!();
+        println!("Most inlinks per non-zero outlink");
+        println!("¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯¯");
+
+        by_degrees.reverse();
+        self.print_links(&by_degrees);
+
+        Ok(())
+    }
+
+    fn print_links(&self, by_degrees: &Vec<(&Page, usize, usize)>) {
+        for (page, od, id) in by_degrees.iter().take(self.top) {
+            println!("{} ({od} out, {id} in)", util::fmt_page(page));
+        }
+    }
+}