ggplot_rs/geom/
histogram.rs

1use crate::aes::Aesthetic;
2use crate::coord::Coord;
3use crate::data::DataFrame;
4use crate::position::identity::PositionIdentity;
5use crate::position::Position;
6use crate::render::backend::{DrawBackend, RectStyle};
7use crate::render::RenderError;
8use crate::scale::ScaleSet;
9use crate::stat::bin::StatBin;
10use crate::stat::Stat;
11use crate::theme::Theme;
12
13use super::{Geom, GeomParams};
14
15/// Histogram geometry (bar chart with StatBin).
16pub struct GeomHistogram {
17    pub bins: usize,
18    pub binwidth: Option<f64>,
19    pub fill: (u8, u8, u8),
20    pub color: (u8, u8, u8),
21    pub alpha: f64,
22}
23
24impl GeomHistogram {
25    /// Set bin width (overrides bins count).
26    pub fn with_binwidth(mut self, width: f64) -> Self {
27        self.binwidth = Some(width);
28        self
29    }
30
31    /// Set number of bins.
32    pub fn with_bins(mut self, bins: usize) -> Self {
33        self.bins = bins;
34        self.binwidth = None;
35        self
36    }
37}
38
39impl Default for GeomHistogram {
40    fn default() -> Self {
41        GeomHistogram {
42            bins: 30,
43            binwidth: None,
44            fill: (97, 156, 255),
45            color: (50, 50, 50),
46            alpha: 1.0,
47        }
48    }
49}
50
51impl Geom for GeomHistogram {
52    fn draw(
53        &self,
54        data: &DataFrame,
55        coord: &dyn Coord,
56        scales: &ScaleSet,
57        _theme: &Theme,
58        backend: &mut dyn DrawBackend,
59    ) -> Result<(), RenderError> {
60        let xmin_col = data.column("xmin");
61        let xmax_col = data.column("xmax");
62        let y_col = data
63            .column("y")
64            .ok_or(RenderError::MissingAesthetic("y".into()))?;
65
66        let plot_area = backend.plot_area();
67        let x_scale = scales.get(&Aesthetic::X);
68        let y_scale = scales.get(&Aesthetic::Y);
69
70        for i in 0..data.nrows() {
71            let (left_n, right_n) = match (xmin_col, xmax_col) {
72                (Some(xmin), Some(xmax)) => {
73                    let ln = x_scale.map(|s| s.map(&xmin[i])).unwrap_or(0.0);
74                    let rn = x_scale.map(|s| s.map(&xmax[i])).unwrap_or(1.0);
75                    (ln, rn)
76                }
77                _ => {
78                    // Fall back to x column with small width
79                    let x_col = data
80                        .column("x")
81                        .ok_or(RenderError::MissingAesthetic("x".into()))?;
82                    let nx = x_scale.map(|s| s.map(&x_col[i])).unwrap_or(0.0);
83                    (nx - 0.02, nx + 0.02)
84                }
85            };
86
87            let ny = y_scale.map(|s| s.map(&y_col[i])).unwrap_or(0.0);
88            let ny_base = y_scale
89                .map(|s| s.map(&crate::data::Value::Float(0.0)))
90                .unwrap_or(0.0);
91
92            let (left_px, top_px) = coord.transform((left_n, ny), &plot_area);
93            let (right_px, bottom_px) = coord.transform((right_n, ny_base), &plot_area);
94
95            // Hover tooltip: the bin range and its count.
96            let cnt = super::tip_value(&y_col[i]);
97            let tip = match (xmin_col, xmax_col) {
98                (Some(lo), Some(hi)) => format!(
99                    "[{}, {}): {cnt}",
100                    super::tip_value(&lo[i]),
101                    super::tip_value(&hi[i])
102                ),
103                _ => format!("count: {cnt}"),
104            };
105            backend.set_tooltip(Some(tip));
106
107            backend.draw_rect(
108                (left_px, top_px.min(bottom_px)),
109                (right_px, top_px.max(bottom_px)),
110                &RectStyle {
111                    fill: Some(self.fill),
112                    stroke: Some(self.color),
113                    stroke_width: 0.5,
114                    alpha: self.alpha,
115                    clip: true,
116                },
117            )?;
118        }
119        backend.set_tooltip(None);
120
121        Ok(())
122    }
123
124    fn required_aes(&self) -> Vec<Aesthetic> {
125        vec![Aesthetic::X]
126    }
127
128    fn default_stat(&self) -> Box<dyn Stat> {
129        let mut stat = StatBin {
130            bins: self.bins,
131            binwidth: self.binwidth,
132        };
133        if let Some(bw) = self.binwidth {
134            stat = stat.with_binwidth(bw);
135        }
136        Box::new(stat)
137    }
138
139    fn default_position(&self) -> Box<dyn Position> {
140        Box::new(PositionIdentity)
141    }
142
143    fn default_params(&self) -> GeomParams {
144        GeomParams::default()
145    }
146
147    fn name(&self) -> &str {
148        "histogram"
149    }
150
151    fn include_zero_baseline(&self) -> bool {
152        true
153    }
154
155    fn set_series_color(&mut self, color: (u8, u8, u8)) {
156        self.fill = color;
157    }
158}
ggplot_rs/geom/histogram.rs

ggplot_rs/geom/
histogram.rs
