numcodecs_asinh/
lib.rs

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
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
//! [![CI Status]][workflow] [![MSRV]][repo] [![Latest Version]][crates.io] [![Rust Doc Crate]][docs.rs] [![Rust Doc Main]][docs]
//!
//! [CI Status]: https://img.shields.io/github/actions/workflow/status/juntyr/numcodecs-rs/ci.yml?branch=main
//! [workflow]: https://github.com/juntyr/numcodecs-rs/actions/workflows/ci.yml?query=branch%3Amain
//!
//! [MSRV]: https://img.shields.io/badge/MSRV-1.76.0-blue
//! [repo]: https://github.com/juntyr/numcodecs-rs
//!
//! [Latest Version]: https://img.shields.io/crates/v/numcodecs-asinh
//! [crates.io]: https://crates.io/crates/numcodecs-asinh
//!
//! [Rust Doc Crate]: https://img.shields.io/docsrs/numcodecs-asinh
//! [docs.rs]: https://docs.rs/numcodecs-asinh/
//!
//! [Rust Doc Main]: https://img.shields.io/badge/docs-main-blue
//! [docs]: https://juntyr.github.io/numcodecs-rs/numcodecs_asinh
//!
//! `asinh(x)` codec implementation for the [`numcodecs`] API.

use ndarray::{Array, ArrayBase, ArrayView, ArrayViewMut, Data, Dimension, Zip};
use num_traits::{Float, Signed};
use numcodecs::{
    AnyArray, AnyArrayAssignError, AnyArrayDType, AnyArrayView, AnyArrayViewMut, AnyCowArray,
    Codec, StaticCodec, StaticCodecConfig,
};
use schemars::JsonSchema;
use serde::{Deserialize, Serialize};
use thiserror::Error;

#[derive(Clone, Serialize, Deserialize, JsonSchema)]
#[serde(deny_unknown_fields)]
/// Asinh codec, which applies a quasi-logarithmic transformation on encoding.
///
/// For values close to zero that are within the codec's `linear_width`, the
/// transform is close to linear. For values of larger magnitudes, the
/// transform is asymptotically logarithmic. Unlike a logarithmic transform,
/// this codec supports all finite values, including negative values and zero.
///
/// In detail, the codec calculates `c = asinh(x/w) * w` on encoding and
/// `d = sinh(c/w) * w` on decoding, where `w` is the codec's `linear_width`.
///
/// The codec only supports finite floating point numbers.
pub struct AsinhCodec {
    /// The width of the close-to-zero input value range where the transform is
    /// nearly linear
    linear_width: f64,
}

impl Codec for AsinhCodec {
    type Error = AsinhCodecError;

    fn encode(&self, data: AnyCowArray) -> Result<AnyArray, Self::Error> {
        match data {
            #[allow(clippy::cast_possible_truncation)]
            AnyCowArray::F32(data) => Ok(AnyArray::F32(asinh(data, self.linear_width as f32)?)),
            AnyCowArray::F64(data) => Ok(AnyArray::F64(asinh(data, self.linear_width)?)),
            encoded => Err(AsinhCodecError::UnsupportedDtype(encoded.dtype())),
        }
    }

    fn decode(&self, encoded: AnyCowArray) -> Result<AnyArray, Self::Error> {
        match encoded {
            #[allow(clippy::cast_possible_truncation)]
            AnyCowArray::F32(encoded) => {
                Ok(AnyArray::F32(sinh(encoded, self.linear_width as f32)?))
            }
            AnyCowArray::F64(encoded) => Ok(AnyArray::F64(sinh(encoded, self.linear_width)?)),
            encoded => Err(AsinhCodecError::UnsupportedDtype(encoded.dtype())),
        }
    }

    fn decode_into(
        &self,
        encoded: AnyArrayView,
        decoded: AnyArrayViewMut,
    ) -> Result<(), Self::Error> {
        match (encoded, decoded) {
            #[allow(clippy::cast_possible_truncation)]
            (AnyArrayView::F32(encoded), AnyArrayViewMut::F32(decoded)) => {
                sinh_into(encoded, decoded, self.linear_width as f32)
            }
            (AnyArrayView::F64(encoded), AnyArrayViewMut::F64(decoded)) => {
                sinh_into(encoded, decoded, self.linear_width)
            }
            (encoded @ (AnyArrayView::F32(_) | AnyArrayView::F64(_)), decoded) => {
                Err(AsinhCodecError::MismatchedDecodeIntoArray {
                    source: AnyArrayAssignError::DTypeMismatch {
                        src: encoded.dtype(),
                        dst: decoded.dtype(),
                    },
                })
            }
            (encoded, _decoded) => Err(AsinhCodecError::UnsupportedDtype(encoded.dtype())),
        }
    }
}

impl StaticCodec for AsinhCodec {
    const CODEC_ID: &'static str = "asinh";

    type Config<'de> = Self;

    fn from_config(config: Self::Config<'_>) -> Self {
        config
    }

    fn get_config(&self) -> StaticCodecConfig<Self> {
        StaticCodecConfig::from(self)
    }
}

#[derive(Debug, Error)]
/// Errors that may occur when applying the [`AsinhCodec`].
pub enum AsinhCodecError {
    /// [`AsinhCodec`] does not support the dtype
    #[error("Asinh does not support the dtype {0}")]
    UnsupportedDtype(AnyArrayDType),
    /// [`AsinhCodec`] does not support non-finite (infinite or NaN) floating
    /// point data
    #[error("Asinh does not support non-finite (infinite or NaN) floating point data")]
    NonFiniteData,
    /// [`AsinhCodec`] cannot decode into the provided array
    #[error("Asinh cannot decode into the provided array")]
    MismatchedDecodeIntoArray {
        /// The source of the error
        #[from]
        source: AnyArrayAssignError,
    },
}

/// Compute `asinh(x/w) * w` over the elements of the input `data` array.
///
/// # Errors
///
/// Errors with
/// - [`AsinhCodecError::NonFiniteData`] if any data element is non-finite
///   (infinite or NaN)
pub fn asinh<T: Float + Signed, S: Data<Elem = T>, D: Dimension>(
    data: ArrayBase<S, D>,
    linear_width: T,
) -> Result<Array<T, D>, AsinhCodecError> {
    if !Zip::from(&data).all(|x| x.is_finite()) {
        return Err(AsinhCodecError::NonFiniteData);
    }

    let mut data = data.into_owned();
    data.mapv_inplace(|x| (x / linear_width).asinh() * linear_width);

    Ok(data)
}

/// Compute `sinh(x/w) * w` over the elements of the input `data` array.
///
/// # Errors
///
/// Errors with
/// - [`AsinhCodecError::NonFiniteData`] if any data element is non-finite
///   (infinite or NaN)
pub fn sinh<T: Float, S: Data<Elem = T>, D: Dimension>(
    data: ArrayBase<S, D>,
    linear_width: T,
) -> Result<Array<T, D>, AsinhCodecError> {
    if !Zip::from(&data).all(|x| x.is_finite()) {
        return Err(AsinhCodecError::NonFiniteData);
    }

    let mut data = data.into_owned();
    data.mapv_inplace(|x| (x / linear_width).sinh() * linear_width);

    Ok(data)
}

#[allow(clippy::needless_pass_by_value)]
/// Compute `sinh(x/w) * w` over the elements of the input `data` array and
/// write them into the `out`put array.
///
/// # Errors
///
/// Errors with
/// - [`AsinhCodecError::NonFiniteData`] if any data element is non-finite
///   (infinite or NaN)
/// - [`AsinhCodecError::MismatchedDecodeIntoArray`] if the `data` array's shape
///   does not match the `out`put array's shape
pub fn sinh_into<T: Float, D: Dimension>(
    data: ArrayView<T, D>,
    mut out: ArrayViewMut<T, D>,
    linear_width: T,
) -> Result<(), AsinhCodecError> {
    if data.shape() != out.shape() {
        return Err(AsinhCodecError::MismatchedDecodeIntoArray {
            source: AnyArrayAssignError::ShapeMismatch {
                src: data.shape().to_vec(),
                dst: out.shape().to_vec(),
            },
        });
    }

    if !Zip::from(&data).all(|x| x.is_finite()) {
        return Err(AsinhCodecError::NonFiniteData);
    }

    // iteration must occur in synchronised (standard) order
    for (d, o) in data.iter().zip(out.iter_mut()) {
        *o = ((*d) / linear_width).sinh() * linear_width;
    }

    Ok(())
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn roundtrip() -> Result<(), AsinhCodecError> {
        let data = (-1000..1000).map(f64::from).collect::<Vec<_>>();
        let data = Array::from_vec(data);

        let encoded = asinh(data.view(), 1.0)?;

        for (r, e) in data.iter().zip(encoded.iter()) {
            assert_eq!((*r).asinh().to_bits(), (*e).to_bits());
        }

        let decoded = sinh(encoded, 1.0)?;

        for (r, d) in data.iter().zip(decoded.iter()) {
            assert!(((*r) - (*d)).abs() < 1e-12);
        }

        Ok(())
    }

    #[test]
    fn roundtrip_widths() -> Result<(), AsinhCodecError> {
        let data = (-1000..1000).map(f64::from).collect::<Vec<_>>();
        let data = Array::from_vec(data);

        for linear_width in [-100.0, -10.0, -1.0, -0.1, 0.1, 1.0, 10.0, 100.0] {
            let encoded = asinh(data.view(), linear_width)?;
            let decoded = sinh(encoded, linear_width)?;

            for (r, d) in data.iter().zip(decoded.iter()) {
                assert!(((*r) - (*d)).abs() < 1e-12);
            }
        }

        Ok(())
    }
}