step.parameters

Parameters are injected into the command by replacing any Valohai parameter placeholders defined further below. Good examples of parameters would be “learning rate” number or “network layout” string.

A parameter in parameters has 2 required and 5 optional properties:

• name: the parameter name, shown on the user interface
• type: the parameter type, valid values are float, integer, string and flag
• pass-as: (optional) how the parameter is passed to the command
• description: (optional) more detailed human-readable description of the parameter
• default: (optional) the default value of the parameter
• optional: (optional) marks that this input is optional and the value can be left undefined
• choices: (optional) list of alternative values, shown as a dropdown menu in the UI

Using the flag parameter

optional has no effect for the flag type. It either exists or doesn’t. If it’s always on, you can type it into the command.

If pass-as is not defined, the parameter is passed as --<PARAMETER_NAME>={v}, you can customize this by specifying {v} in the pass-as e.g. -t {v} where {v} becomes the actual value.

flag type defaults to just --<PARAMETER_NAME> when set to true. When set to false, nothing is passed.

The note above implies that when you want to pass a flag with the value false, you will need to use a special version of the pass-as property.

pass-true-as: --<PARAMETER_NAME>=true
pass-false-as: --<PARAMETER_NAME>=false

choices

The choices property lets you to define a list of alternative values for the parameter. The value for the execution can be chosen by using a dropdown menu in the UI.

parameters:
- name: color
  type: string
  default: blue
  description: Choose a color
  optional: false
  choices:
    - blue
    - red
    - green

{parameters} placeholder

{parameters} injects all parameters to its position in the commands.

For example:

- step:
    name: train-model
    image: python:3.6
    command:
      - python train.py {parameters}
    parameters:
      - name: max-steps
        type: integer
        description: Number of steps to run the trainer
        default: 300
      - name: learning-rate
        type: float
        pass-as: --lr={v}
        description: Initial learning rate
        default: 0.001
      - name: architecture
        type: string
        pass-as: arc {v}
        default: 10xRELU-SoftMax
        optional: true

The above would generate the following command by default:

python train.py --max-steps=300 --lr=0.001 arc 10xRELU-SoftMax

{parameter:<NAME>} placeholder

You can also use singular parameters using the {parameter:<NAME>} syntax.

For example:

- step:
    name: preprocess-and-train
    image: python:3.6
    command:
      - python preprocess.py {parameter:train-split}
      - python train.py {parameter:learning-rate}
    parameters:
      - name: train-split
        type: integer
        default: 80
      - name: learning-rate
        pass-as: --lr={v}
        type: float
        default: 0.001

The above would generate the following commands by default:

python preprocess.py --train-split=80
python train.py --lr=0.001

{parameter-value:<NAME>} placeholder

If you wish to ignore pass-as definition, you can use {parameter-value:<NAME>} to pass only the parameter value. This is essentially the same as defining pass-as: "{v}".

For example:

- step:
    name: preprocess
    image: python:3.6
    command:
      - python preprocess.py {parameter-value:train-split} {parameter-value:style}
    parameters:
      - name: train-split
        type: integer
        default: 80
      - name: style
        pass-as: -s={v}
        type: string
        default: nested

The above would generate the following command by default:

python preprocess.py 80 nested