extra viz

src/histogram.rs

@@ -0,0 +1,58 @@
+// SPDX-FileCopyrightText: 2025 Joost van der Laan <[email protected]>
+//
+// SPDX-License-Identifier: AGPL-3.0-only
+
+use anyhow::Result;
+use plotters::prelude::*;
+
+use crate::viz::StockData;
+
+pub fn create_market_cap_histogram(stocks: &[StockData], output_path: &str) -> Result<()> {
+    let root = BitMapBackend::new(output_path, (1024, 768)).into_drawing_area();
+    root.fill(&WHITE)?;
+
+    let market_caps: Vec<f64> = stocks.iter().map(|s| s.market_cap_eur).collect();
+    let max_cap = market_caps.iter().fold(f64::NEG_INFINITY, |a, &b| a.max(b));
+    let min_cap = market_caps.iter().fold(f64::INFINITY, |a, &b| a.min(b));
+
+    // Create 20 bins for the histogram
+    const NUM_BINS: usize = 20;
+    let bin_size = (max_cap - min_cap) / NUM_BINS as f64;
+    let mut bins = vec![0; NUM_BINS];
+
+    // Count values in each bin
+    for &cap in &market_caps {
+        let bin_index = ((cap - min_cap) / bin_size).floor() as usize;
+        let bin_index = bin_index.min(NUM_BINS - 1); // Handle edge case for max value
+        bins[bin_index] += 1;
+    }
+
+    let max_count = *bins.iter().max().unwrap_or(&0);
+
+    let mut chart = ChartBuilder::on(&root)
+        .caption("Market Cap Distribution", ("sans-serif", 30))
+        .margin(10)
+        .x_label_area_size(40)
+        .y_label_area_size(60)
+        .build_cartesian_2d(0..NUM_BINS, 0..max_count + 1)?;
+
+    chart
+        .configure_mesh()
+        .x_desc("Market Cap (EUR)")
+        .y_desc("Number of Companies")
+        .x_label_formatter(&|x| {
+            let value = min_cap + (*x as f64 * bin_size);
+            format!("{:.1}B", value / 1e9) // Convert to billions
+        })
+        .draw()?;
+
+    chart.draw_series(
+        Histogram::vertical(&chart)
+            .style(BLUE.filled())
+            .margin(0)
+            .data(bins.iter().enumerate().map(|(i, &count)| (i, count))),
+    )?;
+
+    root.present()?;
+    Ok(())
+}