maxPooling1dLayer

1-D max pooling layer

Description

A 1-D max pooling layer performs downsampling by dividing the input into 1-D pooling regions, then computing the maximum of each region.

The dimension that the layer pools over depends on the layer input:

• For time series and vector sequence input (data with three dimensions corresponding to the channels, observations, and time steps), the layer pools over the time dimension.

• For 1-D image input (data with three dimensions corresponding to the spatial pixels, channels, and observations), the layer pools over the spatial dimension.

• For 1-D image sequence input (data with four dimensions corresponding to the spatial pixels, channels, observations, and time steps), the layer pools over the spatial dimension.

Creation

Syntax

layer = maxPooling1dLayer(poolSize)

layer = maxPooling1dLayer(poolSize,Name=Value)

Description

layer = maxPooling1dLayer(poolSize) creates a 1-D max pooling layer and sets the PoolSize property.

layer = maxPooling1dLayer(poolSize,Name=Value) also specifies the padding or sets the Stride and Name properties using one or more optional name-value arguments. For example, maxPooling1dLayer(3,Padding=1,Stride=2) creates a 1-D max pooling layer with a pool size of 3, a stride of 2, and padding of size 1 on both the left and right of the input.

Input Arguments

Name-Value Pair Arguments

Specify optional pairs of arguments as Name1=Value1,...,NameN=ValueN, where Name is the argument name and Value is the corresponding value. Name-value arguments must appear after other arguments, but the order of the pairs does not matter.

Example: maxPooling1dLayer(2,Padding=1) creates a 1-D max pooling layer with a pool size of 3 and padding of size 1 on the left and right of the layer input.

Padding — Padding to apply to input

[0 0] (default) | "same" | nonnegative integer | vector of nonnegative integers

Padding to apply to the input, specified as one of the following:

• "same" — Apply padding such that the output size is ceil(inputSize/stride), where inputSize is the length of the input. When Stride is 1, the output is the same size as the input.

• Nonnegative integer sz — Add padding of size sz to both ends of the input.

• Vector [l r] of nonnegative integers — Add padding of size l to the left and r to the right of the input.

Example: Padding=[2 1] adds padding of size 2 to the left and size 1 to the right.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | char | string

Properties

Max Pooling

PoolSize — Width of pooling regions

positive integer

Width of the pooling regions, specified as a positive integer.

The width of the pooling regions PoolSize must be greater than or equal to the padding dimensions PaddingSize.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

Stride — Step size for traversing input

1 (default) | positive integer

Step size for traversing the input, specified as a positive integer.

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

PaddingSize — Size of padding

[0 0] (default) | vector of two nonnegative integers

Size of padding to apply to each side of the input, specified as a vector [l r] of two nonnegative integers, where l is the padding applied to the left and r is the padding applied to the right.

When you create a layer, use the Padding name-value argument to specify the padding size.

Data Types: double

PaddingMode — Method to determine padding size

'manual' (default) | 'same'

This property is read-only.

Method to determine padding size, specified as one of the following:

• 'manual' – Pad using the integer or vector specified by Padding.

• 'same' – Apply padding such that the output size is ceil(inputSize/Stride), where inputSize is the length of the input. When Stride is 1, the output is the same as the input.

To specify the layer padding, use the Padding name-value argument.

Data Types: char

Layer

Name — Layer name

'' (default) | character vector | string scalar

Layer name, specified as a character vector or a string scalar. For Layer array input, the trainNetwork, assembleNetwork, layerGraph, and dlnetwork functions automatically assign names to layers with Name set to ''.

Data Types: char | string

NumInputs — Number of inputs

1 (default)

This property is read-only.

Number of inputs of the layer. This layer accepts a single input only.

Data Types: double

InputNames — Input names

{'in'} (default)

This property is read-only.

Input names of the layer. This layer accepts a single input only.

Data Types: cell

NumOutputs — Number of outputs

1 (default)

This property is read-only.

Number of outputs of the layer. This layer has a single output only.

Data Types: double

OutputNames — Output names

{'out'} (default)

This property is read-only.

Output names of the layer. This layer has a single output only.

Data Types: cell

Examples

Create 1-D Max Pooling Layer

Create a 1-D max pooling layer with a pool size of 3.

layer = maxPooling1dLayer(3);

Include a 1-D max pooling layer in a layer array.

layers = [
    sequenceInputLayer(12)
    convolution1dLayer(11,96)
    reluLayer
    maxPooling1dLayer(3)
    convolution1dLayer(11,96)
    reluLayer
    globalMaxPooling1dLayer
    fullyConnectedLayer(10)
    softmaxLayer
    classificationLayer]

layers = 
  10x1 Layer array with layers:

     1   ''   Sequence Input           Sequence input with 12 dimensions
     2   ''   Convolution              96 11 convolutions with stride 1 and padding [0  0]
     3   ''   ReLU                     ReLU
     4   ''   1-D Max Pooling          Max pooling with pool size 3, stride 1, and padding [0  0]
     5   ''   Convolution              96 11 convolutions with stride 1 and padding [0  0]
     6   ''   ReLU                     ReLU
     7   ''   1-D Global Max Pooling   1-D global max pooling
     8   ''   Fully Connected          10 fully connected layer
     9   ''   Softmax                  softmax
    10   ''   Classification Output    crossentropyex

Algorithms

1-D Max Pooling Layer

A 1-D max pooling layer performs downsampling by dividing the input into 1-D pooling regions, then computing the maximum of each region. The layer pools the input by moving the pooling regions along the input horizontally.

The dimension that the layer pools over depends on the layer input:

• For time series and vector sequence input (data with three dimensions corresponding to the channels, observations, and time steps), the layer pools over the time dimension.

• For 1-D image input (data with three dimensions corresponding to the spatial pixels, channels, and observations), the layer pools over the spatial dimension.

• For 1-D image sequence input (data with four dimensions corresponding to the spatial pixels, channels, observations, and time steps), the layer pools over the spatial dimension.