ggplot_rs/geom/
smooth.rs

1use crate::aes::Aesthetic;
2use crate::coord::Coord;
3use crate::data::{DataFrame, Value};
4use crate::position::identity::PositionIdentity;
5use crate::position::Position;
6use crate::render::backend::{DrawBackend, LineStyle, Linetype, PointShape, PointStyle, RectStyle};
7use crate::render::RenderError;
8use crate::scale::ScaleSet;
9use crate::stat::smooth::{SmoothMethod, StatSmooth};
10use crate::stat::Stat;
11use crate::theme::Theme;
12
13use super::{Geom, GeomParams};
14
15/// Smooth line with optional confidence ribbon.
16pub struct GeomSmooth {
17    pub color: (u8, u8, u8),
18    pub fill: (u8, u8, u8),
19    pub line_width: f64,
20    pub alpha: f64,
21    pub se: bool,
22    pub n_points: usize,
23    pub method: SmoothMethod,
24}
25
26impl Default for GeomSmooth {
27    fn default() -> Self {
28        GeomSmooth {
29            color: (51, 102, 204),
30            fill: (51, 102, 204),
31            line_width: 1.5,
32            alpha: 0.2,
33            se: true,
34            n_points: 80,
35            method: SmoothMethod::Lm,
36        }
37    }
38}
39
40impl GeomSmooth {
41    /// Use LOESS smoothing with the given span.
42    pub fn loess(mut self, span: f64) -> Self {
43        self.method = SmoothMethod::Loess { span };
44        self
45    }
46
47    /// Use penalized B-spline (P-spline) GAM smoothing — ggplot2's
48    /// `method = "gam"`, backed by anofox-regression with GCV-selected λ.
49    #[cfg(feature = "regression")]
50    pub fn gam(mut self) -> Self {
51        self.method = SmoothMethod::Gam;
52        self
53    }
54}
55
56impl Geom for GeomSmooth {
57    fn draw(
58        &self,
59        data: &DataFrame,
60        coord: &dyn Coord,
61        scales: &ScaleSet,
62        _theme: &Theme,
63        backend: &mut dyn DrawBackend,
64    ) -> Result<(), RenderError> {
65        let x_col = data
66            .column("x")
67            .ok_or(RenderError::MissingAesthetic("x".into()))?;
68        let y_col = data
69            .column("y")
70            .ok_or(RenderError::MissingAesthetic("y".into()))?;
71        let ymin_col = data.column("ymin");
72        let ymax_col = data.column("ymax");
73        let color_col = data.column("color");
74        let fill_col = data.column("fill");
75
76        let plot_area = backend.plot_area();
77        let x_scale = scales.get(&Aesthetic::X);
78        let y_scale = scales.get(&Aesthetic::Y);
79
80        // If there's a color/fill aesthetic, draw separate smooths per group
81        if let Some(cc) = color_col.or(fill_col) {
82            let mut groups: Vec<(String, Vec<usize>)> = Vec::new();
83            for (i, v) in cc.iter().enumerate() {
84                let key = v.to_group_key();
85                if let Some(entry) = groups.iter_mut().find(|(k, _)| k == &key) {
86                    entry.1.push(i);
87                } else {
88                    groups.push((key, vec![i]));
89                }
90            }
91
92            for (_, indices) in &groups {
93                let first_idx = indices[0];
94
95                // Determine colors from mapped aesthetics
96                let line_color = color_col
97                    .and_then(|c| scales.map_color(&Aesthetic::Color, &c[first_idx]))
98                    .unwrap_or(self.color);
99                let ribbon_fill = fill_col
100                    .and_then(|f| scales.map_color(&Aesthetic::Fill, &f[first_idx]))
101                    .or_else(|| {
102                        color_col.and_then(|c| scales.map_color(&Aesthetic::Color, &c[first_idx]))
103                    })
104                    .unwrap_or(self.fill);
105
106                // Draw confidence ribbon
107                if self.se {
108                    if let (Some(ymin), Some(ymax)) = (ymin_col, ymax_col) {
109                        let mut upper_points: Vec<(f64, f64)> = Vec::new();
110                        let mut lower_points: Vec<(f64, f64)> = Vec::new();
111
112                        for &i in indices {
113                            let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
114                            let ny_max = y_scale.map(|s| s.map(&ymax[i])).unwrap_or(0.0);
115                            let ny_min = y_scale.map(|s| s.map(&ymin[i])).unwrap_or(0.0);
116
117                            upper_points.push(coord.transform((nx, ny_max), &plot_area));
118                            lower_points.push(coord.transform((nx, ny_min), &plot_area));
119                        }
120
121                        let mut polygon = upper_points;
122                        lower_points.reverse();
123                        polygon.extend(lower_points);
124
125                        if polygon.len() >= 3 {
126                            backend.draw_polygon(
127                                &polygon,
128                                &RectStyle {
129                                    fill: Some(ribbon_fill),
130                                    stroke: None,
131                                    stroke_width: 0.0,
132                                    alpha: self.alpha,
133                                    clip: true,
134                                },
135                            )?;
136                        }
137                    }
138                }
139
140                // Draw fitted line
141                let points: Vec<(f64, f64)> = indices
142                    .iter()
143                    .map(|&i| {
144                        let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
145                        let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
146                        coord.transform((nx, ny), &plot_area)
147                    })
148                    .collect();
149
150                if points.len() >= 2 {
151                    backend.draw_line(
152                        &points,
153                        &LineStyle {
154                            color: line_color,
155                            alpha: 1.0,
156                            width: self.line_width,
157                            linetype: Linetype::Solid,
158                        },
159                    )?;
160                    draw_hover_marks(
161                        backend, &points, indices, x_col, y_col, ymin_col, ymax_col, line_color,
162                    )?;
163                }
164            }
165        } else {
166            // No grouping — original behavior with fixed colors
167
168            // Draw confidence ribbon first (behind line)
169            if self.se {
170                if let (Some(ymin), Some(ymax)) = (ymin_col, ymax_col) {
171                    let mut upper_points: Vec<(f64, f64)> = Vec::new();
172                    let mut lower_points: Vec<(f64, f64)> = Vec::new();
173
174                    for i in 0..data.nrows() {
175                        let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
176                        let ny_max = y_scale.map(|s| s.map(&ymax[i])).unwrap_or(0.0);
177                        let ny_min = y_scale.map(|s| s.map(&ymin[i])).unwrap_or(0.0);
178
179                        upper_points.push(coord.transform((nx, ny_max), &plot_area));
180                        lower_points.push(coord.transform((nx, ny_min), &plot_area));
181                    }
182
183                    // Build polygon: upper left-to-right, then lower right-to-left
184                    let mut polygon = upper_points;
185                    lower_points.reverse();
186                    polygon.extend(lower_points);
187
188                    if polygon.len() >= 3 {
189                        backend.draw_polygon(
190                            &polygon,
191                            &RectStyle {
192                                fill: Some(self.fill),
193                                stroke: None,
194                                stroke_width: 0.0,
195                                alpha: self.alpha,
196                                clip: true,
197                            },
198                        )?;
199                    }
200                }
201            }
202
203            // Draw fitted line
204            let points: Vec<(f64, f64)> = (0..data.nrows())
205                .map(|i| {
206                    let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
207                    let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
208                    coord.transform((nx, ny), &plot_area)
209                })
210                .collect();
211
212            if points.len() >= 2 {
213                backend.draw_line(
214                    &points,
215                    &LineStyle {
216                        color: self.color,
217                        alpha: 1.0,
218                        width: self.line_width,
219                        linetype: Linetype::Solid,
220                    },
221                )?;
222                let rows: Vec<usize> = (0..data.nrows()).collect();
223                draw_hover_marks(
224                    backend, &points, &rows, x_col, y_col, ymin_col, ymax_col, self.color,
225                )?;
226            }
227        }
228
229        Ok(())
230    }
231
232    fn required_aes(&self) -> Vec<Aesthetic> {
233        vec![Aesthetic::X, Aesthetic::Y]
234    }
235
236    fn default_stat(&self) -> Box<dyn Stat> {
237        Box::new(StatSmooth {
238            n_points: self.n_points,
239            se: self.se,
240            method: self.method.clone(),
241        })
242    }
243
244    fn default_position(&self) -> Box<dyn Position> {
245        Box::new(PositionIdentity)
246    }
247
248    fn default_params(&self) -> GeomParams {
249        GeomParams::default()
250    }
251
252    fn name(&self) -> &str {
253        "smooth"
254    }
255
256    fn set_series_color(&mut self, color: (u8, u8, u8)) {
257        self.color = color;
258        self.fill = color;
259    }
260}
261
262/// The fitted curve is drawn as a single path and so carries no per-point
263/// marks. Emit a sparse set of transparent hover points along it — each tagged
264/// with the fitted `ŷ` (and the CI when present) — so the axis pointer can read
265/// the smoother on hover, mirroring `geom_density`.
266#[allow(clippy::too_many_arguments)]
267fn draw_hover_marks(
268    backend: &mut dyn DrawBackend,
269    points: &[(f64, f64)],
270    rows: &[usize],
271    x_col: &[Value],
272    y_col: &[Value],
273    ymin_col: Option<&[Value]>,
274    ymax_col: Option<&[Value]>,
275    color: (u8, u8, u8),
276) -> Result<(), RenderError> {
277    let step = (rows.len() / 40).max(1);
278    for (k, &i) in rows.iter().enumerate() {
279        if k % step != 0 {
280            continue;
281        }
282        super::set_mark(
283            backend,
284            Some(smooth_tip(y_col, ymin_col, ymax_col, i)),
285            Some(super::tip_value(&x_col[i])),
286            None,
287            super::raw_value(&y_col[i]),
288        );
289        backend.draw_shape(
290            points[k],
291            0.6,
292            &PointStyle {
293                color,
294                alpha: 0.0,
295                filled: true,
296                shape: PointShape::Circle,
297            },
298        )?;
299    }
300    super::clear_mark(backend);
301    Ok(())
302}
303
304/// `ŷ = <fitted>` plus ` [lo, hi]` when a confidence band is present.
305fn smooth_tip(
306    y_col: &[Value],
307    ymin_col: Option<&[Value]>,
308    ymax_col: Option<&[Value]>,
309    i: usize,
310) -> String {
311    let yv = y_col[i]
312        .as_f64()
313        .map(|f| format!("{f:.3}"))
314        .unwrap_or_default();
315    let ci = match (ymin_col, ymax_col) {
316        (Some(lo), Some(hi)) => match (lo[i].as_f64(), hi[i].as_f64()) {
317            (Some(a), Some(b)) => format!(" [{a:.3}, {b:.3}]"),
318            _ => String::new(),
319        },
320        _ => String::new(),
321    };
322    format!("ŷ = {yv}{ci}")
323}
ggplot_rs/geom/smooth.rs

ggplot_rs/geom/
smooth.rs
