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68 lines
4.0 KiB
68 lines
4.0 KiB
# PaddlePaddle Fluid Source Code Overview
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Examples: https://github.com/PaddlePaddle/Paddle/tree/develop/python/paddle/fluid/tests/book
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Core: https://github.com/PaddlePaddle/Paddle/tree/develop/paddle/fluid/framework
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Operator: https://github.com/PaddlePaddle/Paddle/tree/develop/paddle/fluid/operators
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Memory: https://github.com/PaddlePaddle/Paddle/tree/develop/paddle/fluid/memory
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Platform: https://github.com/PaddlePaddle/Paddle/tree/develop/paddle/fluid/platform
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# Compile Time
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The following **defines** the NN. The definition goes into this [protocol buffer](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/framework.proto).
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```python
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x = fluid.layers.data(name='x', shape=[13], dtype='float32')
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y = fluid.layers.data(name='y', shape=[1], dtype='float32')
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y_predict = fluid.layers.fc(input=x, size=1, act=None)
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cost = fluid.layers.square_error_cost(input=y_predict, label=y)
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avg_cost = fluid.layers.mean(x=cost)
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sgd_optimizer = fluid.optimizer.SGD(learning_rate=0.001)
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sgd_optimizer.minimize(avg_cost)
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```
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- Variables: `x`, `y`, `y_predict`, `cost` and `avg_cost`. [Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/framework.py#)
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- Layers: `fluid.layers.data`, `fluid.layers.fc` and `fluid.layers.mean` are layers. [Python](https://github.com/PaddlePaddle/Paddle/tree/develop/python/paddle/fluid/layers)
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- Every Layer has one or more operators and variables/parameters
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- All the operators are defined at [`paddle/fluid/operators/`](https://github.com/PaddlePaddle/Paddle/tree/develop/paddle/fluid/operators). Other worth-looking files:
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- Base class: [`paddle/fluid/framework/operator.h`](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/operator.h)
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- Operator Registration: [`paddle/fluid/framework/op_registry.h`](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/op_registry.h)
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- Operator Lookup: [`paddle/fluid/framework/op_info.h`](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/op_info.h)
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- Optimizer: `fluid.optimizer.SGD`. It does the following
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- Add backward operators. [[Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/backward.py)]
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- Add optimizer operators. [[Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/optimizer.py)]
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# Run Time
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The following **evaluates** the NN. Instantiates all the variables, operators.
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```python
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place = fluid.CPUPlace()
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feeder = fluid.DataFeeder(place=place, feed_list=[x, y])
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exe = fluid.Executor(place)
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# Allocate memory. Initialize Parameter.
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exe.run(fluid.default_startup_program())
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# Allocate memory. Do computation.
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exe.run(fluid.default_main_program(),
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feed=feeder.feed(data),
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fetch_list=[avg_cost])
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```
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- Place: `place`. one of CPU, GPU or FPGA. [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/platform/place.h)
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- The device handle are at [paddle/fluid/platform/device_context.h](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/platform/device_context.h)
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- Executor: `fluid.Executor(place)`. [[Python](https://github.com/PaddlePaddle/Paddle/blob/develop/python/paddle/fluid/executor.py), [C++](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/executor.cc)]
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- Feeds the data: `feed=feeder.feed(data)`
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- Evaluates all the operators
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- Fetches the result: `fetch_list=[avg_cost]`
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- Other worth looking files:
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- Scope: [paddle/fluid/framework/scope.h](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/scope.h). Where all the variables live
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- Variable: [paddle/fluid/framework/variable.h](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/variable.h). Where all the data (most likely tensors) live
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- Tensor: [paddle/fluid/framework/tensor.h](https://github.com/PaddlePaddle/Paddle/blob/develop/paddle/fluid/framework/tensor.h). Where we allocate memory through [`paddle/fluid/memory/`](https://github.com/PaddlePaddle/Paddle/tree/develop/paddle/fluid/memory)
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