burn_nn/modules/pool/
max_pool2d.rs

1use crate::conv::checks::check_same_padding_support;
2use burn_core as burn;
3
4use crate::PaddingConfig2d;
5use burn::config::Config;
6use burn::module::{Content, DisplaySettings, ModuleDisplay};
7use burn::module::{Ignored, Module};
8use burn::tensor::Tensor;
9use burn::tensor::backend::Backend;
10
11use burn::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    /// If true, use ceiling instead of floor for output size calculation.
32    #[config(default = "false")]
33    pub ceil_mode: bool,
34}
35
36/// Applies a 2D max pooling over input tensors.
37///
38/// Should be created with [MaxPool2dConfig](MaxPool2dConfig).
39#[derive(Module, Clone, Debug)]
40#[module(custom_display)]
41pub struct MaxPool2d {
42    /// The strides.
43    pub stride: [usize; 2],
44    /// The size of the kernel.
45    pub kernel_size: [usize; 2],
46    /// The padding configuration.
47    pub padding: Ignored<PaddingConfig2d>,
48    /// The dilation.
49    pub dilation: [usize; 2],
50    /// If true, use ceiling instead of floor for output size calculation.
51    pub ceil_mode: bool,
52}
53
54impl ModuleDisplay for MaxPool2d {
55    fn custom_settings(&self) -> Option<DisplaySettings> {
56        DisplaySettings::new()
57            .with_new_line_after_attribute(false)
58            .optional()
59    }
60
61    fn custom_content(&self, content: Content) -> Option<Content> {
62        content
63            .add("kernel_size", &alloc::format!("{:?}", &self.kernel_size))
64            .add("stride", &alloc::format!("{:?}", &self.stride))
65            .add("padding", &self.padding)
66            .add("dilation", &alloc::format!("{:?}", &self.dilation))
67            .add("ceil_mode", &self.ceil_mode)
68            .optional()
69    }
70}
71
72impl MaxPool2dConfig {
73    /// Initialize a new [max pool 2d](MaxPool2d) module.
74    pub fn init(&self) -> MaxPool2d {
75        if self.padding == PaddingConfig2d::Same {
76            check_same_padding_support(&self.kernel_size);
77        }
78        MaxPool2d {
79            stride: self.strides,
80            kernel_size: self.kernel_size,
81            padding: Ignored(self.padding.clone()),
82            dilation: self.dilation,
83            ceil_mode: self.ceil_mode,
84        }
85    }
86}
87
88impl MaxPool2d {
89    /// Applies the forward pass on the input tensor.
90    ///
91    /// See [max_pool2d](burn::tensor::module::max_pool2d) for more information.
92    ///
93    /// # Shapes
94    ///
95    /// - input: `[batch_size, channels, height_in, width_in]`
96    /// - output: `[batch_size, channels, height_out, width_out]`
97    pub fn forward<B: Backend>(&self, input: Tensor<B, 4>) -> Tensor<B, 4> {
98        let [_batch_size, _channels_in, height_in, width_in] = input.dims();
99        let padding =
100            self.padding
101                .calculate_padding_2d(height_in, width_in, &self.kernel_size, &self.stride);
102
103        max_pool2d(
104            input,
105            self.kernel_size,
106            self.stride,
107            padding,
108            self.dilation,
109            self.ceil_mode,
110        )
111    }
112}
113
114#[cfg(test)]
115mod tests {
116    use super::*;
117    use rstest::rstest;
118
119    #[test]
120    #[should_panic = "Same padding with an even kernel size is not supported"]
121    fn same_with_even_kernel_is_invalid() {
122        let config = MaxPool2dConfig::new([2, 2]).with_padding(PaddingConfig2d::Same);
123        let _ = config.init();
124    }
125
126    #[test]
127    fn display() {
128        let config = MaxPool2dConfig::new([3, 3]);
129
130        let layer = config.init();
131
132        assert_eq!(
133            alloc::format!("{layer}"),
134            "MaxPool2d {kernel_size: [3, 3], stride: [3, 3], padding: Valid, dilation: [1, 1], ceil_mode: false}"
135        );
136    }
137
138    #[rstest]
139    #[case([2, 2])]
140    #[case([1, 2])]
141    fn default_strides_match_kernel_size(#[case] kernel_size: [usize; 2]) {
142        let config = MaxPool2dConfig::new(kernel_size);
143
144        assert_eq!(
145            config.strides, kernel_size,
146            "Expected strides ({:?}) to match kernel size ({:?}) in default MaxPool2dConfig::new constructor",
147            config.strides, config.kernel_size
148        );
149    }
150}
burn_nn/modules/pool/max_pool2d.rs

burn_nn/modules/pool/
max_pool2d.rs
