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}