ndarray/
impl_dyn.rs

1// Copyright 2018 bluss and ndarray developers.
2//
3// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
4// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
5// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
6// option. This file may not be copied, modified, or distributed
7// except according to those terms.
8
9//! Methods for dynamic-dimensional arrays.
10use crate::imp_prelude::*;
11
12/// # Methods for Dynamic-Dimensional Arrays
13impl<A, S> ArrayBase<S, IxDyn>
14where S: Data<Elem = A>
15{
16    /// Insert new array axis of length 1 at `axis`, modifying the shape and
17    /// strides in-place.
18    ///
19    /// **Panics** if the axis is out of bounds.
20    ///
21    /// ```
22    /// use ndarray::{Axis, arr2, arr3};
23    ///
24    /// let mut a = arr2(&[[1, 2, 3], [4, 5, 6]]).into_dyn();
25    /// assert_eq!(a.shape(), &[2, 3]);
26    ///
27    /// a.insert_axis_inplace(Axis(1));
28    /// assert_eq!(a, arr3(&[[[1, 2, 3]], [[4, 5, 6]]]).into_dyn());
29    /// assert_eq!(a.shape(), &[2, 1, 3]);
30    /// ```
31    #[track_caller]
32    pub fn insert_axis_inplace(&mut self, axis: Axis)
33    {
34        assert!(axis.index() <= self.ndim());
35        self.dim = self.dim.insert_axis(axis);
36        self.strides = self.strides.insert_axis(axis);
37    }
38
39    /// Collapses the array to `index` along the axis and removes the axis,
40    /// modifying the shape and strides in-place.
41    ///
42    /// **Panics** if `axis` or `index` is out of bounds.
43    ///
44    /// ```
45    /// use ndarray::{Axis, arr1, arr2};
46    ///
47    /// let mut a = arr2(&[[1, 2, 3], [4, 5, 6]]).into_dyn();
48    /// assert_eq!(a.shape(), &[2, 3]);
49    ///
50    /// a.index_axis_inplace(Axis(1), 1);
51    /// assert_eq!(a, arr1(&[2, 5]).into_dyn());
52    /// assert_eq!(a.shape(), &[2]);
53    /// ```
54    #[track_caller]
55    pub fn index_axis_inplace(&mut self, axis: Axis, index: usize)
56    {
57        self.collapse_axis(axis, index);
58        self.dim = self.dim.remove_axis(axis);
59        self.strides = self.strides.remove_axis(axis);
60    }
61
62    /// Remove axes of length 1 and return the modified array.
63    ///
64    /// If the array has more the one dimension, the result array will always
65    /// have at least one dimension, even if it has a length of 1.
66    ///
67    /// ```
68    /// use ndarray::{arr1, arr2, arr3};
69    ///
70    /// let a = arr3(&[[[1, 2, 3]], [[4, 5, 6]]]).into_dyn();
71    /// assert_eq!(a.shape(), &[2, 1, 3]);
72    /// let b = a.squeeze();
73    /// assert_eq!(b, arr2(&[[1, 2, 3], [4, 5, 6]]).into_dyn());
74    /// assert_eq!(b.shape(), &[2, 3]);
75    ///
76    /// let c = arr2(&[[1]]).into_dyn();
77    /// assert_eq!(c.shape(), &[1, 1]);
78    /// let d = c.squeeze();
79    /// assert_eq!(d, arr1(&[1]).into_dyn());
80    /// assert_eq!(d.shape(), &[1]);
81    /// ```
82    #[track_caller]
83    pub fn squeeze(self) -> Self
84    {
85        let mut out = self;
86        for axis in (0..out.shape().len()).rev() {
87            if out.shape()[axis] == 1 && out.shape().len() > 1 {
88                out = out.remove_axis(Axis(axis));
89            }
90        }
91        out
92    }
93}
94
95#[cfg(test)]
96mod tests
97{
98    use crate::{arr1, arr2, arr3};
99
100    #[test]
101    fn test_squeeze()
102    {
103        let a = arr3(&[[[1, 2, 3]], [[4, 5, 6]]]).into_dyn();
104        assert_eq!(a.shape(), &[2, 1, 3]);
105
106        let b = a.squeeze();
107        assert_eq!(b, arr2(&[[1, 2, 3], [4, 5, 6]]).into_dyn());
108        assert_eq!(b.shape(), &[2, 3]);
109
110        let c = arr2(&[[1]]).into_dyn();
111        assert_eq!(c.shape(), &[1, 1]);
112
113        let d = c.squeeze();
114        assert_eq!(d, arr1(&[1]).into_dyn());
115        assert_eq!(d.shape(), &[1]);
116    }
117}
ndarray/impl_dyn.rs

ndarray/
impl_dyn.rs
