Source code for cobra.medium.boundary_types

# -*- coding: utf-8 -*-

"""Contains function to identify the type of boundary reactions.

This module uses various heuristics to decide whether a boundary reaction
is an exchange, demand or sink reaction. It mostly orientates on the following

Thiele, I., & Palsson, B. Ø. (2010, January). A protocol for
generating a high-quality genome-scale metabolic reconstruction.
Nature protocols. Nature Publishing Group.

import logging
from collections import Counter

import pandas as pd

from cobra.medium.annotations import compartment_shortlist, excludes, sbo_terms

[docs]LOGGER = logging.getLogger(__name__)
[docs]def find_external_compartment(model): """Find the external compartment in the model. Uses a simple heuristic where the external compartment should be the one with the most exchange reactions. Arguments --------- model : cobra.Model A cobra model. Returns ------- str The putative external compartment. """ if model.boundary: counts = pd.Series(tuple(r.compartments)[0] for r in model.boundary) most = counts.value_counts() most = most.index[most == most.max()].to_series() else: most = None like_external = compartment_shortlist["e"] + ["e"] matches = pd.Series( [co in like_external for co in model.compartments], index=model.compartments ) if matches.sum() == 1: compartment = matches.index[matches][0] "Compartment `%s` sounds like an external compartment. " "Using this one without counting boundary reactions" % compartment ) return compartment elif most is not None and matches.sum() > 1 and matches[most].sum() == 1: compartment = most[matches[most]][0] LOGGER.warning( "There are several compartments that look like an " "external compartment but `%s` has the most boundary " "reactions, so using that as the external " "compartment." % compartment ) return compartment elif matches.sum() > 1: raise RuntimeError( "There are several compartments (%s) that look " "like external compartments but we can't tell " "which one to use. Consider renaming your " "compartments please." ) if most is not None: return most[0] LOGGER.warning( "Could not identify an external compartment by name and" " choosing one with the most boundary reactions. That " "might be complete nonsense or change suddenly. " "Consider renaming your compartments using " "`Model.compartments` to fix this." ) # No info in the model, so give up raise RuntimeError( "The heuristic for discovering an external compartment "
"relies on names and boundary reactions. Yet, there " "are neither compartments with recognized names nor " "boundary reactions in the model." )
[docs]def is_boundary_type(reaction, boundary_type, external_compartment): """Check whether a reaction is an exchange reaction. Arguments --------- reaction : cobra.Reaction The reaction to check. boundary_type : str What boundary type to check for. Must be one of "exchange", "demand", or "sink". external_compartment : str The id for the external compartment. Returns ------- boolean Whether the reaction looks like the requested type. Might be based on a heuristic. """ # Check if the reaction has an annotation. Annotations dominate everything. sbo_term = reaction.annotation.get("sbo", "") if isinstance(sbo_term, list): sbo_term = sbo_term[0] sbo_term = sbo_term.upper() if sbo_term == sbo_terms[boundary_type]: return True if sbo_term in [sbo_terms[k] for k in sbo_terms if k != boundary_type]: return False # Check if the reaction is in the correct compartment (exterior or inside) correct_compartment = external_compartment in reaction.compartments if boundary_type != "exchange": correct_compartment = not correct_compartment # Check if the reaction has the correct reversibility rev_type = True if boundary_type == "demand": rev_type = not reaction.reversibility elif boundary_type == "sink": rev_type = reaction.reversibility return ( reaction.boundary and not any(ex in for ex in excludes[boundary_type]) and correct_compartment and rev_type
[docs]def find_boundary_types(model, boundary_type, external_compartment=None): """Find specific boundary reactions. Arguments --------- model : cobra.Model A cobra model. boundary_type : str What boundary type to check for. Must be one of "exchange", "demand", or "sink". external_compartment : str or None The id for the external compartment. If None it will be detected automatically. Returns ------- list of cobra.reaction A list of likely boundary reactions of a user defined type. """ if not model.boundary: LOGGER.warning( "There are no boundary reactions in this model. " "Therefore specific types of boundary reactions such " "as 'exchanges', 'demands' or 'sinks' cannot be " "identified." ) return [] if external_compartment is None: external_compartment = find_external_compartment(model) return model.reactions.query( lambda r: is_boundary_type(r, boundary_type, external_compartment)