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--- |
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title: Reshape Layer |
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--- |
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# Reshape Layer |
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* Layer type: `Reshape` |
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* [Doxygen Documentation](http://caffe.berkeleyvision.org/doxygen/classcaffe_1_1ReshapeLayer.html) |
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* Header: [`./include/caffe/layers/reshape_layer.hpp`](https://github.com/BVLC/caffe/blob/master/include/caffe/layers/reshape_layer.hpp) |
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* Implementation: [`./src/caffe/layers/reshape_layer.cpp`](https://github.com/BVLC/caffe/blob/master/src/caffe/layers/reshape_layer.cpp) |
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* Input |
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- a single blob with arbitrary dimensions |
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* Output |
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- the same blob, with modified dimensions, as specified by `reshape_param` |
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* Sample |
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layer { |
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name: "reshape" |
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type: "Reshape" |
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bottom: "input" |
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top: "output" |
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reshape_param { |
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shape { |
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dim: 0 # copy the dimension from below |
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dim: 2 |
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dim: 3 |
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dim: -1 # infer it from the other dimensions |
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} |
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} |
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} |
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The `Reshape` layer can be used to change the dimensions of its input, without changing its data. Just like the `Flatten` layer, only the dimensions are changed; no data is copied in the process. |
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Output dimensions are specified by the `ReshapeParam` proto. Positive numbers are used directly, setting the corresponding dimension of the output blob. In addition, two special values are accepted for any of the target dimension values: |
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* **0** means "copy the respective dimension of the bottom layer". That is, if the bottom has 2 as its 1st dimension, the top will have 2 as its 1st dimension as well, given `dim: 0` as the 1st target dimension. |
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* **-1** stands for "infer this from the other dimensions". This behavior is similar to that of -1 in *numpy*'s or `[]` for *MATLAB*'s reshape: this dimension is calculated to keep the overall element count the same as in the bottom layer. At most one -1 can be used in a reshape operation. |
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As another example, specifying `reshape_param { shape { dim: 0 dim: -1 } }` makes the layer behave in exactly the same way as the `Flatten` layer. |
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## Parameters |
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* Parameters (`ReshapeParameter reshape_param`) |
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- Optional: (also see detailed description below) |
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- `shape` |
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* From [`./src/caffe/proto/caffe.proto`](https://github.com/BVLC/caffe/blob/master/src/caffe/proto/caffe.proto): |
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{% highlight Protobuf %} |
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{% include proto/ReshapeParameter.txt %} |
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{% endhighlight %} |
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