B-modes pipeline constructor

A framework for creating B-mode pipelines for the Simons Observatory. Documentation is still under development, but details about how to use this package to create new pipelines can be found below and in CONTRIBUTING.md.

Installation

To install BBPipe, just clone this repository and run

python setup.py install

(add --user if you don't have permissions, which is probably the case at e.g. NERSC).

Once installed, you can test the installation by running it on the current test power-spectrum pipeline (mostly made out of placeholders). To do so, type:

bbpipe test/test.yml

Creating a pipeline

To create a new pipeline, you must create its corresponding pipeline stages, and link them together through a yaml file.

Creating a new pipeline stage involves creating a python module. Note that this module doesn't have to live in this repo, it just has to be accessible by bbpipe when you run it. The new repo must:

• Have an __init__.py file that imports from . all the stages used by your pipeline.
• Have a __main__.py file with the same contents as those from the example bbpower_test directory.
• Each stage is defined by a class which must inherit from bbpipe.PipelineStage. Each class must have its own name, inputs and outputs attributes (essentially the names of the expected input and output data), and a run method that executes the stage.
• The run method should use the parent methods from PipelineStage to get its inputs and outputs etc.

Have a look at the extended comments in bbpower_test/mask_preproc.py for more details on the structure of any pipeline stage.

To create the yaml file that puts your pipeline together, have a look at the test file. This file should contain:

• A list of modules where the different pipeline stages are to be found.
• The launcher type (to be used by PARSL to launch each stage). Currently the only defined launcher type is the local one (i.e. launch jobs serially in your machine), but more will be defined. They will be located in bbpipe/sites.
• The list of stages that define your pipeline. Note that this list is not related to the order in which the different stages will be executed. This order is automatically determined from the inputs and outputs of each pipeline stage.
• The overall inputs of the pipeline (accessible to all pipeline stages).
• A path to another yaml file (config) containing configuration options for each individual pipeline stage as well as global options. Have a look at test/config.yml to see an example for our test power spectrum pipeline.
• A value for the resume parameter, which determines whether a given stage is run if its outputs already exist.
• An output directory where the pipeline outputs will be stored.

Credit

BBPipe is heavily inspired by ceci, a pipeline constructor designed within the LSST DESC by Joe Zuntz, Francois Lanusse and others. BBPipe uses PARSL.