Initial Commit

.gitignore

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+/target

Cargo.lock

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+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "page_rank"
+version = "0.1.0"

Cargo.toml

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+[package]
+name = "page_rank"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

src/main.rs

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+use std::collections::HashMap;
+
+fn main() {
+    let mut pages: Graph<char> = Graph::new();
+    pages.add_page('A');
+    pages.add_page('B');
+    pages.add_page('C');
+    pages.add_page('D');
+    pages.add_page('E');
+
+    println!("{pages:?}");
+    pages.link_page('B', 'A');
+    pages.link_page('C', 'B');
+    pages.link_page('D', 'C');
+    pages.link_page('B', 'D');
+    pages.link_page('E', 'D');
+    pages.link_page('A', 'E');
+    pages.link_page('B', 'E');
+    println!("{pages:?}");
+
+    println!("{:?} -> B", pages.get_links('B'));
+    let p = pages.clone();
+    for page in p.items {
+        println!("PageRank {page} => {}", pages.page_rank(page, 10))
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct Graph<T> {
+    items: Vec<T>,
+    links: HashMap<usize, Vec<usize>>,
+    pub damping_factor: f64
+}
+
+impl<T: Ord + Copy> Graph<T> {
+    pub fn new() -> Self {
+        Graph { items: vec![], links: HashMap::new(), damping_factor: 0.85 }
+    }
+
+    pub fn add_page(&mut self, item: T) {
+        self.items.push(item);
+        self.items.sort();
+        let index = self.find_item(item); 
+        self.links.insert(index, vec![]);
+    }
+    
+    pub fn link_page(&mut self, item: T, link: T) {
+        let item = self.find_item(item);
+        let link = self.find_item(link);
+        self.add_link(item, link)
+    }
+
+    fn add_link(&mut self, item_index: usize, link_index: usize) {
+        self.links.get_mut(&item_index).unwrap().push(link_index);
+    }
+
+    fn find_item(&self, item: T) -> usize {
+        self.items.binary_search(&item).unwrap()
+    }
+
+    pub fn get_links(&self, item: T) -> Vec<T> {
+        let item = self.find_item(item);
+        self.links.get(&item).unwrap()
+            .to_vec().iter().map(|i| self.items[*i]).collect()
+    }
+
+    pub fn page_rank(&self, item: T, depth: i32) -> f64 {
+        if depth == 0 { return 0.0; }
+
+        let links = self.get_links(item);
+        let link_sums: f64 = links.clone().iter().map(
+            |i| self.page_rank(*i, depth - 1) / self.get_links(*i).len() as f64
+        ).sum();
+        return (1.0 - self.damping_factor) + self.damping_factor * link_sums
+    }
+}