Source code for galaxy.workflow.steps

""" This module contains utility methods for reasoning about and ordering
workflow steps.
"""
import math

from galaxy.util.topsort import (
    CycleError,
    topsort,
    topsort_levels,
)


[docs]def attach_ordered_steps(workflow): """Attempt to topologically order steps and attach to workflow. If this fails - the workflow contains cycles so it mark it as such. """ ordered_steps = order_workflow_steps(workflow.steps) workflow.has_cycles = True if ordered_steps: workflow.has_cycles = False workflow.steps = ordered_steps for i, step in enumerate(workflow.steps): step.order_index = i return workflow.has_cycles
[docs]def order_workflow_steps(steps): """ Perform topological sort of the steps, return ordered or None """ position_data_available = bool(steps) for step in steps: if step.subworkflow: attach_ordered_steps(step.subworkflow) if not step.position or "left" not in step.position or "top" not in step.position: position_data_available = False if position_data_available: # find minimum left and top values to normalize position min_left = min(step.position["left"] for step in steps) min_top = min(step.position["top"] for step in steps) # normalize by min_left and min_top for step in steps: step.position = { "left": step.position["left"] - min_left, "top": step.position["top"] - min_top # other position attributes can be discarded if present } steps.sort(key=lambda _: _.position["left"] + _.position["top"]) # order by Euclidean distance to the origin (i.e. pre-normalized (min_left, min_top)) steps.sort(key=lambda _: math.sqrt(_.position["left"] ** 2 + _.position["top"] ** 2)) try: edges = sorted(edgelist_for_workflow_steps(steps)) node_order = topsort(edges) return [steps[i] for i in node_order] except CycleError: return None
[docs]def has_cycles(workflow): try: topsort(sorted(edgelist_for_workflow_steps(workflow.steps))) return False except CycleError: return True
[docs]def edgelist_for_workflow_steps(steps): """ Create a list of tuples representing edges between ``WorkflowStep`` s based on associated ``WorkflowStepConnection`` s """ edges = [] steps_to_index = {step: i for i, step in enumerate(steps)} for step in steps: edges.append((steps_to_index[step], steps_to_index[step])) for conn in step.input_connections: output_index = steps_to_index[conn.output_step] input_index = steps_to_index[conn.input_step] # self connection - a cycle not detectable by topsort function. if output_index == input_index: raise CycleError([], 0, 0) edges.append((output_index, input_index)) return edges
[docs]def order_workflow_steps_with_levels(steps): try: return topsort_levels(edgelist_for_workflow_steps(steps)) except CycleError: return None