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    /// Use a generalized linear model — ggplot2's
56    /// `geom_smooth(method = "glm", method.args = list(family = …))` — e.g.
57    /// `GeomSmooth::default().glm(SmoothFamily::binomial())`. The band is the
58    /// link-scale confidence interval mapped through the inverse link (see
59    /// [`SmoothFamily`](crate::stat::smooth::SmoothFamily)).
60    #[cfg(feature = "regression")]
61    pub fn glm(mut self, family: crate::stat::smooth::SmoothFamily) -> Self {
62        self.method = SmoothMethod::Glm { family };
63        self
64    }
65}
66
67impl Geom for GeomSmooth {
68    fn draw(
69        &self,
70        data: &DataFrame,
71        coord: &dyn Coord,
72        scales: &ScaleSet,
73        _theme: &Theme,
74        backend: &mut dyn DrawBackend,
75    ) -> Result<(), RenderError> {
76        let x_col = data
77            .column("x")
78            .ok_or(RenderError::MissingAesthetic("x".into()))?;
79        let y_col = data
80            .column("y")
81            .ok_or(RenderError::MissingAesthetic("y".into()))?;
82        let ymin_col = data.column("ymin");
83        let ymax_col = data.column("ymax");
84        let color_col = data.column("color");
85        let fill_col = data.column("fill");
86
87        let plot_area = backend.plot_area();
88        let x_scale = scales.get(&Aesthetic::X);
89        let y_scale = scales.get(&Aesthetic::Y);
90
91        // If there's a color/fill aesthetic, draw separate smooths per group
92        if let Some(cc) = color_col.or(fill_col) {
93            let mut groups: Vec<(String, Vec<usize>)> = Vec::new();
94            for (i, v) in cc.iter().enumerate() {
95                let key = v.to_group_key();
96                if let Some(entry) = groups.iter_mut().find(|(k, _)| k == &key) {
97                    entry.1.push(i);
98                } else {
99                    groups.push((key, vec![i]));
100                }
101            }
102
103            for (_, indices) in &groups {
104                let first_idx = indices[0];
105
106                // Determine colors from mapped aesthetics
107                let line_color = color_col
108                    .and_then(|c| scales.map_color(&Aesthetic::Color, &c[first_idx]))
109                    .unwrap_or(self.color);
110                let ribbon_fill = fill_col
111                    .and_then(|f| scales.map_color(&Aesthetic::Fill, &f[first_idx]))
112                    .or_else(|| {
113                        color_col.and_then(|c| scales.map_color(&Aesthetic::Color, &c[first_idx]))
114                    })
115                    .unwrap_or(self.fill);
116
117                // Draw confidence ribbon
118                if self.se {
119                    if let (Some(ymin), Some(ymax)) = (ymin_col, ymax_col) {
120                        let mut upper_points: Vec<(f64, f64)> = Vec::new();
121                        let mut lower_points: Vec<(f64, f64)> = Vec::new();
122
123                        for &i in indices {
124                            let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
125                            let ny_max = y_scale.map(|s| s.map(&ymax[i])).unwrap_or(0.0);
126                            let ny_min = y_scale.map(|s| s.map(&ymin[i])).unwrap_or(0.0);
127
128                            upper_points.push(coord.transform((nx, ny_max), &plot_area));
129                            lower_points.push(coord.transform((nx, ny_min), &plot_area));
130                        }
131
132                        let mut polygon = upper_points;
133                        lower_points.reverse();
134                        polygon.extend(lower_points);
135
136                        if polygon.len() >= 3 {
137                            backend.draw_polygon(
138                                &polygon,
139                                &RectStyle {
140                                    fill: Some(ribbon_fill),
141                                    stroke: None,
142                                    stroke_width: 0.0,
143                                    alpha: self.alpha,
144                                    clip: true,
145                                },
146                            )?;
147                        }
148                    }
149                }
150
151                // Draw fitted line
152                let points: Vec<(f64, f64)> = indices
153                    .iter()
154                    .map(|&i| {
155                        let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
156                        let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
157                        coord.transform((nx, ny), &plot_area)
158                    })
159                    .collect();
160
161                if points.len() >= 2 {
162                    backend.draw_line(
163                        &points,
164                        &LineStyle {
165                            color: line_color,
166                            alpha: 1.0,
167                            width: self.line_width,
168                            linetype: Linetype::Solid,
169                            ..Default::default()
170                        },
171                    )?;
172                    draw_hover_marks(
173                        backend, &points, indices, x_col, y_col, ymin_col, ymax_col, line_color,
174                    )?;
175                }
176            }
177        } else {
178            // No grouping — original behavior with fixed colors
179
180            // Draw confidence ribbon first (behind line)
181            if self.se {
182                if let (Some(ymin), Some(ymax)) = (ymin_col, ymax_col) {
183                    let mut upper_points: Vec<(f64, f64)> = Vec::new();
184                    let mut lower_points: Vec<(f64, f64)> = Vec::new();
185
186                    for i in 0..data.nrows() {
187                        let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
188                        let ny_max = y_scale.map(|s| s.map(&ymax[i])).unwrap_or(0.0);
189                        let ny_min = y_scale.map(|s| s.map(&ymin[i])).unwrap_or(0.0);
190
191                        upper_points.push(coord.transform((nx, ny_max), &plot_area));
192                        lower_points.push(coord.transform((nx, ny_min), &plot_area));
193                    }
194
195                    // Build polygon: upper left-to-right, then lower right-to-left
196                    let mut polygon = upper_points;
197                    lower_points.reverse();
198                    polygon.extend(lower_points);
199
200                    if polygon.len() >= 3 {
201                        backend.draw_polygon(
202                            &polygon,
203                            &RectStyle {
204                                fill: Some(self.fill),
205                                stroke: None,
206                                stroke_width: 0.0,
207                                alpha: self.alpha,
208                                clip: true,
209                            },
210                        )?;
211                    }
212                }
213            }
214
215            // Draw fitted line
216            let points: Vec<(f64, f64)> = (0..data.nrows())
217                .map(|i| {
218                    let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
219                    let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
220                    coord.transform((nx, ny), &plot_area)
221                })
222                .collect();
223
224            if points.len() >= 2 {
225                backend.draw_line(
226                    &points,
227                    &LineStyle {
228                        color: self.color,
229                        alpha: 1.0,
230                        width: self.line_width,
231                        linetype: Linetype::Solid,
232                        ..Default::default()
233                    },
234                )?;
235                let rows: Vec<usize> = (0..data.nrows()).collect();
236                draw_hover_marks(
237                    backend, &points, &rows, x_col, y_col, ymin_col, ymax_col, self.color,
238                )?;
239            }
240        }
241
242        Ok(())
243    }
244
245    fn required_aes(&self) -> Vec<Aesthetic> {
246        vec![Aesthetic::X, Aesthetic::Y]
247    }
248
249    fn default_stat(&self) -> Box<dyn Stat> {
250        Box::new(StatSmooth {
251            n_points: self.n_points,
252            se: self.se,
253            method: self.method.clone(),
254        })
255    }
256
257    fn default_position(&self) -> Box<dyn Position> {
258        Box::new(PositionIdentity)
259    }
260
261    fn default_params(&self) -> GeomParams {
262        GeomParams::default()
263    }
264
265    fn name(&self) -> &str {
266        "smooth"
267    }
268
269    fn set_series_color(&mut self, color: (u8, u8, u8)) {
270        self.color = color;
271        self.fill = color;
272    }
273}
274
275/// The fitted curve is drawn as a single path and so carries no per-point
276/// marks. Emit a sparse set of transparent hover points along it — each tagged
277/// with the fitted `ŷ` (and the CI when present) — so the axis pointer can read
278/// the smoother on hover, mirroring `geom_density`.
279#[allow(clippy::too_many_arguments)]
280fn draw_hover_marks(
281    backend: &mut dyn DrawBackend,
282    points: &[(f64, f64)],
283    rows: &[usize],
284    x_col: &[Value],
285    y_col: &[Value],
286    ymin_col: Option<&[Value]>,
287    ymax_col: Option<&[Value]>,
288    color: (u8, u8, u8),
289) -> Result<(), RenderError> {
290    let step = (rows.len() / 40).max(1);
291    for (k, &i) in rows.iter().enumerate() {
292        if k % step != 0 {
293            continue;
294        }
295        super::set_mark(
296            backend,
297            Some(smooth_tip(y_col, ymin_col, ymax_col, i)),
298            Some(super::tip_value(&x_col[i])),
299            None,
300            super::raw_value(&y_col[i]),
301        );
302        backend.draw_shape(
303            points[k],
304            0.6,
305            &PointStyle {
306                color,
307                alpha: 0.0,
308                filled: true,
309                shape: PointShape::Circle,
310            },
311        )?;
312    }
313    super::clear_mark(backend);
314    Ok(())
315}
316
317/// `ŷ = <fitted>` plus ` [lo, hi]` when a confidence band is present.
318fn smooth_tip(
319    y_col: &[Value],
320    ymin_col: Option<&[Value]>,
321    ymax_col: Option<&[Value]>,
322    i: usize,
323) -> String {
324    let yv = y_col[i]
325        .as_f64()
326        .map(|f| format!("{f:.3}"))
327        .unwrap_or_default();
328    let ci = match (ymin_col, ymax_col) {
329        (Some(lo), Some(hi)) => match (lo[i].as_f64(), hi[i].as_f64()) {
330            (Some(a), Some(b)) => format!(" [{a:.3}, {b:.3}]"),
331            _ => String::new(),
332        },
333        _ => String::new(),
334    };
335    format!("ŷ = {yv}{ci}")
336}
ggplot_rs/geom/smooth.rs

ggplot_rs/geom/
smooth.rs
