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Last pushed: a month ago
Short Description
A GBDX task to train a CNN on labeled image chips
Full Description


A GBDX task that trains a CNN classifier on labeled image chips using the GPU.


Here we run a sample execution of the train-cnn task. Sample inputs are provided on S3 in the locations specified below.

  1. In a Python terminal create a GBDX interface and specify the task input location:

     from gbdxtools import Interface
     from os.path import join
     import uuid
     gbdx = Interface()
     input_location = 's3://gbd-customer-data/32cbab7a-4307-40c8-bb31-e2de32f940c2/platform-stories/train-cnn/'
  2. Create a task instance and set the required inputs:

     cnn_task = gbdx.Task('train-cnn')
     cnn_task.inputs.train_data = join(input_location, 'train_data')
     cnn_task.inputs.bit_depth = '8'
     cnn_task.inputs.nb_epoch = '15'
  3. Create a single-task workflow object and define where the output data should be saved.

     workflow = gbdx.Workflow([cnn_task])
     random_str = str(uuid.uuid4())
     output_location = join('platform-stories/trial-runs', random_str)
     workflow.savedata(cnn_task.outputs.trained_model, output_location)
  4. Execute the workflow and monitor its status as follows:


Input Ports

GBDX input ports can only be of "Directory" or "String" type. Booleans, integers and floats are passed to the task as strings, e.g., "True", "10", "0.001".

Name Type Description Required
train_data directory Contains training images X.npz and corresponding labels y.npz. True
nb_epoch string Number of training epochs to perform during training. Defaults to 10. False
bit_depth string Bit depth of the input images. This parameter is necessary for proper normalization. Defaults to 8. False

Output Ports

Name Type Description
trained_model directory Contains the fully trained model with the architecture stored as model_arch.json and the weights as model_weights.h5.


Build the Docker Image

You need to install Docker.

Clone the repository:

git clone


cd train-cnn
docker build -t train-cnn .

Try out locally

Create a container in interactive mode and mount the sample input under /mnt/work/input/:

docker run --rm -v full/path/to/sample-input:/mnt/work/input -it train-cnn

Then, within the container:

python /

Docker Hub

Login to Docker Hub:

docker login

Tag your image using your username and push it to DockerHub:

docker tag train-cnn yourusername/train-cnn
docker push yourusername/train-cnn

The image name should be the same as the image name under containerDescriptors in train-cnn.json.

Alternatively, you can link this repository to a Docker automated build. Every time you push a change to the repository, the Docker image gets automatically updated.

Register on GBDX

In a Python terminal:

from gbdxtools import Interface

Note: If you change the task image, you need to reregister the task with a higher version number in order for the new image to take effect. Keep this in mind especially if you use Docker automated build.

Docker Pull Command
Source Repository

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