burn_core/nn/pool/
max_pool2d.rs

1use crate as burn;
2use crate::nn::conv::checks::check_same_padding_support;
3
4use crate::config::Config;
5use crate::module::{Content, DisplaySettings, ModuleDisplay};
6use crate::module::{Ignored, Module};
7use crate::nn::PaddingConfig2d;
8use crate::tensor::Tensor;
9use crate::tensor::backend::Backend;
10
11use crate::tensor::module::max_pool2d;
12
13/// Configuration to create a [2D max pooling](MaxPool2d) layer using the [init function](MaxPool2dConfig::init).
14#[derive(Debug, Config)]
15pub struct MaxPool2dConfig {
16    /// The size of the kernel.
17    pub kernel_size: [usize; 2],
18    /// The strides.
19    #[config(default = "kernel_size")]
20    pub strides: [usize; 2],
21    /// The padding configuration.
22    ///
23    /// ### Warning
24    /// Only symmetric padding is currently supported. As such, using `Same` padding with an even kernel
25    /// size is not supported as it will not produce the same output size.
26    #[config(default = "PaddingConfig2d::Valid")]
27    pub padding: PaddingConfig2d,
28    /// The dilation.
29    #[config(default = "[1, 1]")]
30    pub dilation: [usize; 2],
31}
32
33/// Applies a 2D max pooling over input tensors.
34///
35/// Should be created with [MaxPool2dConfig](MaxPool2dConfig).
36#[derive(Module, Clone, Debug)]
37#[module(custom_display)]
38pub struct MaxPool2d {
39    /// The strides.
40    pub stride: [usize; 2],
41    /// The size of the kernel.
42    pub kernel_size: [usize; 2],
43    /// The padding configuration.
44    pub padding: Ignored<PaddingConfig2d>,
45    /// The dilation.
46    pub dilation: [usize; 2],
47}
48
49impl ModuleDisplay for MaxPool2d {
50    fn custom_settings(&self) -> Option<DisplaySettings> {
51        DisplaySettings::new()
52            .with_new_line_after_attribute(false)
53            .optional()
54    }
55
56    fn custom_content(&self, content: Content) -> Option<Content> {
57        content
58            .add("kernel_size", &alloc::format!("{:?}", &self.kernel_size))
59            .add("stride", &alloc::format!("{:?}", &self.stride))
60            .add("padding", &self.padding)
61            .add("dilation", &alloc::format!("{:?}", &self.dilation))
62            .optional()
63    }
64}
65
66impl MaxPool2dConfig {
67    /// Initialize a new [max pool 2d](MaxPool2d) module.
68    pub fn init(&self) -> MaxPool2d {
69        if self.padding == PaddingConfig2d::Same {
70            check_same_padding_support(&self.kernel_size);
71        }
72        MaxPool2d {
73            stride: self.strides,
74            kernel_size: self.kernel_size,
75            padding: Ignored(self.padding.clone()),
76            dilation: self.dilation,
77        }
78    }
79}
80
81impl MaxPool2d {
82    /// Applies the forward pass on the input tensor.
83    ///
84    /// See [max_pool2d](crate::tensor::module::max_pool2d) for more information.
85    ///
86    /// # Shapes
87    ///
88    /// - input: `[batch_size, channels, height_in, width_in]`
89    /// - output: `[batch_size, channels, height_out, width_out]`
90    pub fn forward<B: Backend>(&self, input: Tensor<B, 4>) -> Tensor<B, 4> {
91        let [_batch_size, _channels_in, height_in, width_in] = input.dims();
92        let padding =
93            self.padding
94                .calculate_padding_2d(height_in, width_in, &self.kernel_size, &self.stride);
95
96        max_pool2d(input, self.kernel_size, self.stride, padding, self.dilation)
97    }
98}
99
100#[cfg(test)]
101mod tests {
102    use super::*;
103    use rstest::rstest;
104
105    #[test]
106    #[should_panic = "Same padding with an even kernel size is not supported"]
107    fn same_with_even_kernel_is_invalid() {
108        let config = MaxPool2dConfig::new([2, 2]).with_padding(PaddingConfig2d::Same);
109        let _ = config.init();
110    }
111
112    #[test]
113    fn display() {
114        let config = MaxPool2dConfig::new([3, 3]);
115
116        let layer = config.init();
117
118        assert_eq!(
119            alloc::format!("{}", layer),
120            "MaxPool2d {kernel_size: [3, 3], stride: [3, 3], padding: Valid, dilation: [1, 1]}"
121        );
122    }
123
124    #[rstest]
125    #[case([2, 2])]
126    #[case([1, 2])]
127    fn default_strides_match_kernel_size(#[case] kernel_size: [usize; 2]) {
128        let config = MaxPool2dConfig::new(kernel_size);
129
130        assert_eq!(
131            config.strides, kernel_size,
132            "Expected strides ({:?}) to match kernel size ({:?}) in default MaxPool2dConfig::new constructor",
133            config.strides, config.kernel_size
134        );
135    }
136}
burn_core/nn/pool/max_pool2d.rs

burn_core/nn/pool/
max_pool2d.rs
