1use crate::coord::ranged1d::types::RangedCoordf64;
2use crate::coord::ranged1d::{AsRangedCoord, DefaultFormatting, KeyPointHint, Ranged};
3use std::marker::PhantomData;
4use std::ops::Range;
5
6/// The trait for the type that is able to be presented in the log scale.
7/// This trait is primarily used by [LogRangeExt](struct.LogRangeExt.html).
8pub trait LogScalable: Clone {
9 /// Make the conversion from the type to the floating point number
10 fn as_f64(&self) -> f64;
11 /// Convert a floating point number to the scale
12 fn from_f64(f: f64) -> Self;
13}
14
15macro_rules! impl_log_scalable {
16 (i, $t:ty) => {
17 impl LogScalable for $t {
18 fn as_f64(&self) -> f64 {
19 if *self != 0 {
20 return *self as f64;
21 }
22 // If this is an integer, we should allow zero point to be shown
23 // on the chart, thus we can't map the zero point to inf.
24 // So we just assigning a value smaller than 1 as the alternative
25 // of the zero point.
26 return 0.5;
27 }
28 fn from_f64(f: f64) -> $t {
29 f.round() as $t
30 }
31 }
32 };
33 (f, $t:ty) => {
34 impl LogScalable for $t {
35 fn as_f64(&self) -> f64 {
36 *self as f64
37 }
38 fn from_f64(f: f64) -> $t {
39 f as $t
40 }
41 }
42 };
43}
44
45impl_log_scalable!(i, u8);
46impl_log_scalable!(i, u16);
47impl_log_scalable!(i, u32);
48impl_log_scalable!(i, u64);
49impl_log_scalable!(i, usize);
50
51impl_log_scalable!(i, i8);
52impl_log_scalable!(i, i16);
53impl_log_scalable!(i, i32);
54impl_log_scalable!(i, i64);
55impl_log_scalable!(i, i128);
56impl_log_scalable!(i, isize);
57
58impl_log_scalable!(f, f32);
59impl_log_scalable!(f, f64);
60
61/// Convert a range to a log scale coordinate spec
62pub trait IntoLogRange {
63 /// The type of the value
64 type ValueType: LogScalable;
65
66 /// Make the log scale coordinate
67 fn log_scale(self) -> LogRangeExt<Self::ValueType>;
68}
69
70impl<T: LogScalable> IntoLogRange for Range<T> {
71 type ValueType = T;
72 fn log_scale(self) -> LogRangeExt<T> {
73 LogRangeExt {
74 range: self,
75 zero: 0.0,
76 base: 10.0,
77 }
78 }
79}
80
81/// The logarithmic coordinate decorator.
82/// This decorator is used to make the axis rendered as logarithmically.
83#[derive(Clone)]
84pub struct LogRangeExt<V: LogScalable> {
85 range: Range<V>,
86 zero: f64,
87 base: f64,
88}
89
90impl<V: LogScalable> LogRangeExt<V> {
91 /// Set the zero point of the log scale coordinate. Zero point is the point where we map -inf
92 /// of the axis to the coordinate
93 pub fn zero_point(mut self, value: V) -> Self
94 where
95 V: PartialEq,
96 {
97 self.zero = if V::from_f64(0.0) == value {
98 0.0
99 } else {
100 value.as_f64()
101 };
102
103 self
104 }
105
106 /// Set the base multiplier
107 pub fn base(mut self, base: f64) -> Self {
108 if self.base > 1.0 {
109 self.base = base;
110 }
111 self
112 }
113}
114
115impl<V: LogScalable> From<LogRangeExt<V>> for LogCoord<V> {
116 fn from(spec: LogRangeExt<V>) -> LogCoord<V> {
117 let zero_point = spec.zero;
118 let mut start = spec.range.start.as_f64() - zero_point;
119 let mut end = spec.range.end.as_f64() - zero_point;
120 let negative = if start < 0.0 || end < 0.0 {
121 start = -start;
122 end = -end;
123 true
124 } else {
125 false
126 };
127
128 if start < end {
129 if start == 0.0 {
130 start = start.max(end * 1e-5);
131 }
132 } else if end == 0.0 {
133 end = end.max(start * 1e-5);
134 }
135
136 LogCoord {
137 linear: (start.ln()..end.ln()).into(),
138 logic: spec.range,
139 normalized: start..end,
140 base: spec.base,
141 zero_point,
142 negative,
143 marker: PhantomData,
144 }
145 }
146}
147
148impl<V: LogScalable> AsRangedCoord for LogRangeExt<V> {
149 type CoordDescType = LogCoord<V>;
150 type Value = V;
151}
152
153/// A log scaled coordinate axis
154pub struct LogCoord<V: LogScalable> {
155 linear: RangedCoordf64,
156 logic: Range<V>,
157 normalized: Range<f64>,
158 base: f64,
159 zero_point: f64,
160 negative: bool,
161 marker: PhantomData<V>,
162}
163
164impl<V: LogScalable> LogCoord<V> {
165 fn value_to_f64(&self, value: &V) -> f64 {
166 let fv: f64 = value.as_f64() - self.zero_point;
167 if self.negative {
168 -fv
169 } else {
170 fv
171 }
172 }
173
174 fn f64_to_value(&self, fv: f64) -> V {
175 let fv: f64 = if self.negative { -fv } else { fv };
176 V::from_f64(fv + self.zero_point)
177 }
178
179 fn is_inf(&self, fv: f64) -> bool {
180 let fv: f64 = if self.negative { -fv } else { fv };
181 let a: V = V::from_f64(fv + self.zero_point);
182 let b: V = V::from_f64(self.zero_point);
183
184 (V::as_f64(&a) - V::as_f64(&b)).abs() < f64::EPSILON
185 }
186}
187
188impl<V: LogScalable> Ranged for LogCoord<V> {
189 type FormatOption = DefaultFormatting;
190 type ValueType = V;
191
192 fn map(&self, value: &V, limit: (i32, i32)) -> i32 {
193 let fv = self.value_to_f64(value);
194 let value_ln = fv.ln();
195 self.linear.map(&value_ln, limit)
196 }
197
198 fn key_points<Hint: KeyPointHint>(&self, hint: Hint) -> Vec<Self::ValueType> {
199 let max_points = hint.max_num_points();
200
201 let base = self.base;
202 let base_ln = base.ln();
203
204 let Range { mut start, mut end } = self.normalized;
205
206 if start > end {
207 std::mem::swap(&mut start, &mut end);
208 }
209
210 let bold_count = ((end / start).ln().abs() / base_ln).floor().max(1.0) as usize;
211
212 let light_density = if max_points < bold_count {
213 0
214 } else {
215 let density = 1 + (max_points - bold_count) / bold_count;
216 let mut exp = 1;
217 while exp * 10 <= density {
218 exp *= 10;
219 }
220 exp - 1
221 };
222
223 let mut multiplier = base;
224 let mut cnt = 1;
225 while max_points < bold_count / cnt {
226 multiplier *= base;
227 cnt += 1;
228 }
229
230 let mut ret = vec![];
231 let mut val = (base).powf((start.ln() / base_ln).ceil());
232
233 while val <= end {
234 if !self.is_inf(val) {
235 ret.push(self.f64_to_value(val));
236 }
237 for i in 1..=light_density {
238 let v = val
239 * (1.0
240 + multiplier / f64::from(light_density as u32 + 1) * f64::from(i as u32));
241 if v > end {
242 break;
243 }
244 if !self.is_inf(val) {
245 ret.push(self.f64_to_value(v));
246 }
247 }
248 val *= multiplier;
249 }
250
251 ret
252 }
253
254 fn range(&self) -> Range<V> {
255 self.logic.clone()
256 }
257}
258
259/// The logarithmic coordinate decorator.
260/// This decorator is used to make the axis rendered as logarithmically.
261#[deprecated(note = "LogRange is deprecated, use IntoLogRange trait method instead")]
262#[derive(Clone)]
263pub struct LogRange<V: LogScalable>(pub Range<V>);
264
265#[allow(deprecated)]
266impl<V: LogScalable> AsRangedCoord for LogRange<V> {
267 type CoordDescType = LogCoord<V>;
268 type Value = V;
269}
270
271#[allow(deprecated)]
272impl<V: LogScalable> From<LogRange<V>> for LogCoord<V> {
273 fn from(range: LogRange<V>) -> LogCoord<V> {
274 range.0.log_scale().into()
275 }
276}
277
278#[cfg(test)]
279mod test {
280 use super::*;
281 #[test]
282 fn regression_test_issue_143() {
283 let range: LogCoord<f64> = (1.0..5.0).log_scale().into();
284
285 range.key_points(100);
286 }
287}
288