ggplot-rs 0.3.0

A Rust implementation of ggplot2's Grammar of Graphics
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87

use crate::render::Rect;

use super::Coord;

/// Polar coordinate system.
///
/// Maps one aesthetic to angle and the other to radius.
/// - `theta = "x"` (default): x maps to angle, y to radius (pie charts, wind roses)
/// - `theta = "y"`: y maps to angle, x to radius (Coxcomb charts)
pub struct CoordPolar {
    /// Which variable maps to angle: "x" or "y".
    pub theta: String,
    /// Start angle in radians (0 = 12 o'clock position).
    pub start: f64,
    /// Direction: 1 = clockwise, -1 = counterclockwise.
    pub direction: f64,
}

impl CoordPolar {
    pub fn new() -> Self {
        CoordPolar {
            theta: "x".to_string(),
            start: 0.0,
            direction: 1.0,
        }
    }

    pub fn theta(mut self, theta: &str) -> Self {
        self.theta = theta.to_string();
        self
    }

    pub fn start(mut self, start: f64) -> Self {
        self.start = start;
        self
    }

    pub fn direction(mut self, dir: f64) -> Self {
        self.direction = dir;
        self
    }
}

impl Default for CoordPolar {
    fn default() -> Self {
        Self::new()
    }
}

impl Coord for CoordPolar {
    fn transform(&self, point: (f64, f64), plot_area: &Rect) -> (f64, f64) {
        let (nx, ny) = point;

        // Determine which normalized value maps to angle vs radius
        let (angle_norm, radius_norm) = if self.theta == "x" {
            (nx, ny)
        } else {
            (ny, nx)
        };

        // Convert to angle (full circle = 2π)
        let angle = self.start + self.direction * angle_norm * std::f64::consts::TAU;

        // Radius: fraction of the available radius (half the smaller dimension)
        let max_radius = plot_area.width.min(plot_area.height) / 2.0;
        let radius = radius_norm * max_radius;

        // Center of the polar plot
        let cx = plot_area.x + plot_area.width / 2.0;
        let cy = plot_area.y + plot_area.height / 2.0;

        // Convert polar to Cartesian pixel coordinates
        // angle=0 points up (12 o'clock), increases clockwise
        let px = cx + radius * angle.sin();
        let py = cy - radius * angle.cos();

        (px, py)
    }

    fn gridlines(&self) -> bool {
        false
    }

    fn is_flipped(&self) -> bool {
        false
    }
}