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pytorch-lightning/docs/examples/Examples.md
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David Kossnick c0bd203cff Fix broken link in Examples Readme (#327)
It now points to the current examples folder.
2019-10-08 07:39:54 -04:00

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### Template model definition
In 99% of cases you want to just copy [one of the examples](https://github.com/williamFalcon/pytorch-lightning/tree/master/examples) to start a new lightningModule and change the core of what your model is actually trying to do.
```bash
# get a copy of the module template
wget https://raw.githubusercontent.com/williamFalcon/pytorch-lightning/master/examples/new_project_templates/lightning_module_template.py
```
---
### Trainer Example
** \_\_main__ function**
Normally, we want to let the \_\_main__ function start the training.
Inside the main we parse training arguments with whatever hyperparameters we want. Your LightningModule will have a
chance to add hyperparameters.
```{.python}
from test_tube import HyperOptArgumentParser
if __name__ == '__main__':
# use default args given by lightning
root_dir = os.path.split(os.path.dirname(sys.modules['__main__'].__file__))[0]
parent_parser = HyperOptArgumentParser(strategy='random_search', add_help=False)
add_default_args(parent_parser, root_dir)
# allow model to overwrite or extend args
parser = ExampleModel.add_model_specific_args(parent_parser)
hyperparams = parser.parse_args()
# train model
main(hyperparams)
```
**Main Function**
The main function is your entry into the program. This is where you init your model, checkpoint directory, and launch the training.
The main function should have 3 arguments:
- hparams: a configuration of hyperparameters.
- slurm_manager: Slurm cluster manager object (can be None)
- dict: for you to return any values you want (useful in meta-learning, otherwise set to _)
```python
def main(hparams, cluster, results_dict):
"""
Main training routine specific for this project
:param hparams:
:return:
"""
# build model
model = MyLightningModule(hparams)
# configure trainer
trainer = Trainer()
# train model
trainer.fit(model)
```
The __main__ function will start training on your **main** function. If you use the HyperParameterOptimizer
in hyper parameter optimization mode, this main function will get one set of hyperparameters. If you use it as a simple
argument parser you get the default arguments in the argument parser.
So, calling main(hyperparams) runs the model with the default argparse arguments.
```{.python}
main(hyperparams)
```
---
#### CPU hyperparameter search
```{.python}
# run a grid search over 20 hyperparameter combinations.
hyperparams.optimize_parallel_cpu(
main_local,
nb_trials=20,
nb_workers=1
)
```
---
#### Hyperparameter search on a single or multiple GPUs
```{.python}
# run a grid search over 20 hyperparameter combinations.
hyperparams.optimize_parallel_gpu(
main_local,
nb_trials=20,
nb_workers=1,
gpus=[0,1,2,3]
)
```
---
#### Hyperparameter search on a SLURM HPC cluster
```{.python}
def optimize_on_cluster(hyperparams):
# enable cluster training
cluster = SlurmCluster(
hyperparam_optimizer=hyperparams,
log_path=hyperparams.tt_save_path,
test_tube_exp_name=hyperparams.tt_name
)
# email for cluster coms
cluster.notify_job_status(email='add_email_here', on_done=True, on_fail=True)
# configure cluster
cluster.per_experiment_nb_gpus = hyperparams.per_experiment_nb_gpus
cluster.job_time = '48:00:00'
cluster.gpu_type = '1080ti'
cluster.memory_mb_per_node = 48000
# any modules for code to run in env
cluster.add_command('source activate pytorch_lightning')
# name of exp
job_display_name = hyperparams.tt_name.split('_')[0]
job_display_name = job_display_name[0:3]
# run hopt
print('submitting jobs...')
cluster.optimize_parallel_cluster_gpu(
main,
nb_trials=hyperparams.nb_hopt_trials,
job_name=job_display_name
)
# run cluster hyperparameter search
optimize_on_cluster(hyperparams)
```