ggplot_rs/position/
stack.rs

1use crate::data::{DataFrame, Value};
2
3use super::{Position, PositionParams};
4
5/// Stack bars/areas on top of each other.
6pub struct PositionStack;
7
8impl Position for PositionStack {
9    fn compute(&self, data: &mut DataFrame, _params: &PositionParams) {
10        // Group by x, accumulate y values
11        let x_col = match data.column("x") {
12            Some(c) => c.to_vec(),
13            None => return,
14        };
15        let y_col = match data.column("y") {
16            Some(c) => c.to_vec(),
17            None => return,
18        };
19
20        // Build cumulative sums per x group
21        let mut x_cumsum: Vec<(String, f64)> = Vec::new();
22        let mut new_y = Vec::with_capacity(y_col.len());
23        let mut ymin_vals = Vec::with_capacity(y_col.len());
24
25        for (x, y) in x_col.iter().zip(y_col.iter()) {
26            let x_key = x.to_group_key();
27            let y_val = y.as_f64().unwrap_or(0.0);
28
29            let base = x_cumsum
30                .iter()
31                .find(|(k, _)| k == &x_key)
32                .map(|(_, v)| *v)
33                .unwrap_or(0.0);
34
35            ymin_vals.push(Value::Float(base));
36            new_y.push(Value::Float(base + y_val));
37
38            if let Some(entry) = x_cumsum.iter_mut().find(|(k, _)| k == &x_key) {
39                entry.1 += y_val;
40            } else {
41                x_cumsum.push((x_key, y_val));
42            }
43        }
44
45        if let Some(col) = data.column_mut("y") {
46            *col = new_y;
47        }
48        if !data.has_column("ymin") {
49            data.add_column("ymin".to_string(), ymin_vals);
50        } else if let Some(col) = data.column_mut("ymin") {
51            *col = ymin_vals;
52        }
53    }
54
55    fn name(&self) -> &str {
56        "stack"
57    }
58}
ggplot_rs/position/stack.rs

ggplot_rs/position/
stack.rs
