Side outputs

Methods normally pass their processed dataset to the next method. Some methods also produce supplementary values, called side outputs, which can be used as parameters by methods later in the pipeline. A common example is passing a calculated centre of rotation to a reconstruction method.

Fig. 10 The processed dataset follows the main pipeline, while the named side output is passed to a later method parameter.

Define and reference a side output

The producing method requires:

• a unique id;

• a side_outputs mapping from the method’s output name to a pipeline name.

The consuming method refers to the value using ${{id.side_outputs.name}}:

- method: find_center_vo
  module_path: httomolibgpu.recon.rotation
  parameters:
    ind: null
    smin: -50
    smax: 50
    srad: 6.0
    step: 0.25
    ratio: 0.5
    drop: 20
  id: centering
  side_outputs:
    cor: centre_of_rotation

- method: FBP3d_tomobar
  module_path: httomolibgpu.recon.algorithm
  parameters:
    center: ${{centering.side_outputs.centre_of_rotation}}
    filter_freq_cutoff: 1.0
    recon_size: null
    recon_mask_radius: 0.95

The referenced method must appear before the method that uses its output, and each explicit id must be unique within the pipeline.

Note

Side outputs and their references are generated automatically by the YAML generator. They normally do not need to be changed when adapting a generated pipeline.