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A machine learning library for PyTorch
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Help wanted

Cortex is under heavy development. It's functional, but may not fit your needs yet. If you are interested in helping, email us or submit a PR.

(some) Outstanding issues:

  • Need custom data iterator functionality within custom models
  • torchtext integration needed
  • Missing unit tests


Build Status

Cortex is a wrapper around Pytorch that makes training, managing, and visualizing models more convenient.



 cortex is currently only tested on Python 3.5 and 3.6
Visdom (optional)
 $pip install visdom  

From Source

 $git clone 
 $cd cortex 
 $pip install .


Visdom Server (optional)

Cortex has built-in visualization functionality, and currently we support only Visdom (though development for torchvision options is welcome). This is optional, but highly recommended if you wish to use visualization tools within cortex.

To get started with visdom, start a Visdom server and look for server address in the output. By default, the server's address is http://localhost:8097.

 $python -m visdom.server  

For more details, see

Experiment Configuration

The first thing to do is to set up the config.yaml. This file is user-specific, and will tell cortex everything user-specific regarding data locations, visualation, and output locations. This helps your code in cortex be more distributable, as the overhead of dataset locations is handled here.

In order to get started, just run:

$cortex setup

You will be prompted for several locations on your file system. Do not worry if you don't know the locations of all the datasets you wish to add. This can be re-run to add additional datasets.


The first step is to check out cortex from the command line. Simply type:

$ cortex --help
setup                                         Setup cortex configuration.
GAN                                           Generative adversarial network.
VAE                                           Variational autoencder.
AdversarialAutoencoder                        Adversarial Autoencoder
Autoencoder                                   Simple autoencder model.
ALI                                           Adversarially learned inference.
ImageClassification                           Basic image classifier.
ImageAttributeClassification                  Basic image classifier.
GAN_MINE                                      GAN + MINE.

And many more coming.


There are many command-line options in cortex:

  -h, --help                                      show this help message and exit
  -o OUT_PATH, --out_path OUT_PATH                Output path directory. All model results will go
                                                  here. If a new directory, a new one will be
                                                  created, as long as parent exists.
  -n NAME, --name NAME                            Name of the experiment. If given, base name of
                                                  output directory will be `--name`. If not given,
                                                  name will be the base name of the `--out_path`
  -r RELOAD, --reload RELOAD                      Path to model to reload.
  -R RELOADS [RELOADS ...], --reloads RELOADS [RELOADS ...]
  -M LOAD_MODELS, --load_models LOAD_MODELS       Path to model to reload. Does not load args, info,
  -m META, --meta META
  -c CONFIG_FILE, --config_file CONFIG_FILE       Configuration yaml file. See `exps/` for examples
  -k, --clean                                     Cleans the output directory. This cannot be
  -v VERBOSITY, --verbosity VERBOSITY             Verbosity of the logging. (0, 1, 2)
  -d DEVICE, --device DEVICE
Usage Example

To run an experiment from the Cortex built-in GAN architecture on the CIFAR10 dataset,

$cortex GAN --d.source CIFAR10 --d.copy_to_local

Custom demos

While cortex has built-in functionality, but it is meant to meant to be used with your own modules. An example of making a model that works with cortex can be found at: and

Documentation on the API can be found here:

For instance, the demo autoencoder can be used as:

python cortex/demos/ --help

A walkthrough a custom classifier:

Let's look a little more closely at the autoencoder demo above to see what's going on. cortex relies on using and overriding methods of plugins classes.

First, let's look at the methods, build, routine, and visualize. These are special methods for the plugin that can be overridden to change the behavior of your model for your needs.

The signature of these functions look like:

    def build(self, dim_z=64, dim_encoder_out=64):
    def routine(self, inputs, targets, ae_criterion=F.mse_loss):
    def visualize(self, inputs, targets):

Each of these functions have arguments and keyword arguments. Note that the keyword arguments showed up in the help in the above example. This is part of the functionality of cortex: it manages your hyperparameters to these functions, organizes them, and provides command line control automatically. Even the docstrings are used in the command line, so other users can get the usage docs directly from there.

The arguments are data, which are to be manipulated as needed in those methods. These are for the most part handled automatically, but all of these methods can be used as normal functions as well.

Building models

The build function takes the hyperparameters and sets networks.

class Autoencoder(nn.Module):
    def __init__(self, encoder, decoder):
        super(Autoencoder, self).__init__()
        self.encoder = encoder
        self.decoder = decoder

    def forward(self, x, nonlinearity=None):
        encoded = self.encoder(x)
        decoded = self.decoder(encoded)
        return decoded

    def build(self, dim_z=64, dim_encoder_out=64):
        encoder = nn.Sequential(
            nn.Linear(28, 256),
            nn.Linear(256, 28),
        decoder = nn.Sequential(
            nn.Linear(28, 256),
            nn.Linear(256, 28),
            nn.Sigmoid()) = Autoencoder(encoder, decoder)

All that's being done here is the hyperparameters are being used to create an instance of an nn.Module subclass, which is being added to the set of "nets". Note that they keyword ae is very important, as this is going to be how you retrieve your nets and define their losses farther down.

Also note that cortex only currently supports nn.Module subclasses from Pytorch.

Defining losses and results

Adding losses and results from your model is easy, just compute your graph given you models and data, then add the losses and results by setting those members:

    def routine(self, inputs, targets, ae_criterion=F.mse_loss):
        encoded =
        outputs =
        r_loss = ae_criterion(
            outputs, inputs, size_average=False) / inputs.size(0) = r_loss

Additional results can be added similarly. For instance, in the demo classifier:

    def routine(self, inputs, targets, criterion=nn.CrossEntropyLoss()):
        classifier = self.nets.classifier

        outputs = classifier(inputs)
        predicted = torch.max(F.log_softmax(outputs, dim=1).data, 1)[1]

        loss = criterion(outputs, targets)
        correct = 100. * predicted.eq(
   / targets.size(0)

        self.losses.classifier = loss
        self.results.accuracy = correct


Cortex allows for visualization using visdom, and this can be defined in a similar way as above:

    def visualize(self, images, inputs, targets):
        predicted = self.predict(inputs)
        self.add_image(, labels=(,,

See the ModelPlugin API for more more details.

Putting it together

Finally, we can specify default arguments:

    defaults = dict(
            batch_size=dict(train=64, test=64), inputs=dict(inputs='images')),
        optimizer=dict(optimizer='Adam', learning_rate=1e-4),

and then add to __main__:

if __name__ == '__main__':
    autoencoder = AE()

And that's it. cortex also allows for lower-level functions to be overridden (e.g., train_step, eval_step, train_loop, etc) with more customizability coming soon. For more examples of usage, see the built-in models:

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