# Network Morphism for Automatic Model Architecture Search in NNI
The Network Morphism is a build-in Tuner using network morphism techniques to search and evaluate the new network architecture. This example shows us how to use it to find good model architectures for deep learning.

## How to run this example?

### 1. Training framework support

The network morphism now is framework-based, and we have not implemented the framework-free methods. The training frameworks which we have supported yet are PyTorch and Keras. If you get familiar with the intermediate JSON format, you can build your own model in your own training framework. In the future, we will change to intermediate format from JSON to ONNX in order to get a [standard intermediate representation spec](https://github.com/onnx/onnx/blob/master/docs/IR.md).


### 2. Install the requirements

```bash
# install the requirements packages
cd examples/trials/network_morphism/
pip install -r requirements.txt
```

### 3. Update configuration

Modify `examples/trials/network_morphism/cifar10/config.yml` to fit your own task, note that searchSpacePath is not required in our configuration. Here is the default configuration:

```yaml
authorName: default
experimentName: example_cifar10-network-morphism
trialConcurrency: 1
maxExecDuration: 48h
maxTrialNum: 200
#choice: local, remote, pai
trainingServicePlatform: local
#choice: true, false
useAnnotation: false
tuner:
  #choice: TPE, Random, Anneal, Evolution, BatchTuner, NetworkMorphism
  #SMAC (SMAC should be installed through nnictl)
  builtinTunerName: NetworkMorphism
  classArgs:
    #choice: maximize, minimize
    optimize_mode: maximize
    #for now, this tuner only supports cv domain
    task: cv
    #modify to fit your input image width
    input_width: 32
    #modify to fit your input image channel
    input_channel: 3
    #modify to fit your number of classes
    n_output_node: 10
trial:
  # your own command here
  command: python3 cifar10_keras.py
  codeDir: .
  gpuNum: 0
```

In the "trial" part, if you want to use GPU to perform the architecture search, change `gpuNum` from `0` to `1`. You need to increase the `maxTrialNum` and `maxExecDuration`, according to how long you want to wait for the search result.

`trialConcurrency` is the number of trials running concurrently, which is the number of GPUs you want to use, if you are setting `gpuNum` to 1.

### 4. Call "json\_to\_graph()" function in your own code

Modify your code and call "json\_to\_graph()" function to build a pytorch model or keras model from received json  string. Here is the simple example.

```python
import nni
from nni.networkmorphism_tuner.graph import json_to_graph

def build_graph_from_json(ir_model_json):
    """build a pytorch model from json representation
    """
    graph = json_to_graph(ir_model_json)
    model = graph.produce_torch_model()
    return model

# trial get next parameter from network morphism tuner
RCV_CONFIG = nni.get_next_parameter()
# call the function to build pytorch model or keras model
net = build_graph_from_json(RCV_CONFIG)

# training procedure
# ....

# report the final accuracy to NNI
nni.report_final_result(best_acc)
```

### 5. Submit this job

```bash
# You can use NNI command tool "nnictl" to create the a job which submit to the NNI
# finally you successfully commit a Network Morphism Job to NNI
nnictl create --config config.yml
```

## Trial Examples

The trial has some examples which can guide you which located in `examples/trials/network_morphism/`. You can refer to it and modify to your own task. Hope this will help you to build your code.

### FashionMNIST

`Fashion-MNIST` is a dataset of [Zalando](https://jobs.zalando.com/tech/)'s article images—consisting of a training set of 60,000 examples and a test set of 10,000 examples. Each example is a 28x28 grayscale image, associated with a label from 10 classes. It is a modern image classification dataset widely used to replacing MNIST as a baseline dataset, because the dataset MNIST is too easy and overused.

There are two examples, [FashionMNIST-keras.py](./FashionMNIST/FashionMNIST_keras.py) and [FashionMNIST-pytorch.py](./FashionMNIST/FashionMNIST_pytorch.py). Attention, you should change the `input_width` to 28 and `input_channel` to 1 in `config.yml` for this dataset.

### Cifar10

The `CIFAR-10` dataset [Canadian Institute For Advanced Research](https://www.cifar.ca/) is a collection of images that are commonly used to train machine learning and computer vision algorithms. It is one of the most widely used datasets for machine learning research. The CIFAR-10 dataset contains 60,000 32x32 color images in 10 different classes.

There are two examples, [cifar10-keras.py](./cifar10/cifar10_keras.py) and [cifar10-pytorch.py](./cifar10/cifar10_pytorch.py). The value `input_width` is 32 and the value `input_channel` is 3 in `config.yml` for this dataset.