Simple Parameter Estimation

This is an example of how to configure a simple parameter estimation using pycotools. We first create a toy model for demonstration, then simulate some experimental data from it and fit it back to the model, using pycotools for configuration.

import os, glob
import pandas, numpy
import matplotlib.pyplot as plt
import seaborn
from pycotools3 import model, tasks, viz
seaborn.set_context(context='talk')

## Choose a directory for our model and analysis
working_directory = os.path.dirname(__file__)

## In this model, A gets reversibly converted to B but the backwards reaction is additionally regulated by C.
## B is reversibly converted into C.
antimony_string = """
model simple_parameter_estimation()
    compartment Cell = 1;

    A in Cell;
    B in Cell;
    C in Cell;

    // reactions
    R1: A => B ; Cell * k1 * A;
    R2: B => A ; Cell * k2 * B * C;
    R3: B => C ; Cell * k3 * B;
    R4: C => B ; Cell * k4 * C;

    // initial concentrations
    A = 100;
    B = 1;
    C = 1;

    // reaction parameters
    k1 = 0.1;
    k2 = 0.1;
    k3 = 0.1;
    k4 = 0.1;
end
"""

copasi_file = os.path.join(working_directory, 'example_model.cps')

## build model
with model.BuildAntimony(copasi_file) as builder:
    mod = builder.load(antimony_string)

assert isinstance(mod, model.Model)

## simulate some data, returns a pandas.DataFrame
data = mod.simulate(0, 20, 1)

## write data to file
experiment_filename = os.path.join(working_directory, 'experiment_data.txt')
data.to_csv(experiment_filename)

## We now have a model and some experimental data and can
## configure a parameter estimation

Parameter estimation configuration in pycotools3 revolves around the tasks.ParameterEstimation.Config object which is the input to the parameter estimation task. The object necessarily takes a lot of manual configuration to ensure it is flexible enough for any parameter estimation configuration. However, the ParameterEstimation.Context class is a tool for simplifying the construction of a Config object.

with tasks.ParameterEstimation.Context(mod, experiment_filename, context='s', parameters='g') as context:
    context.set('separator', ',')
    context.set('run_mode', True)
    context.set('randomize_start_values', True)
    context.set('method', 'genetic_algorithm')
    context.set('population_size', 100)
    context.set('lower_bound', 1e-1)
    context.set('upper_bound', 1e1)

    config = context.get_config()

pe = tasks.ParameterEstimation(config)

data = viz.Parse(pe).data
print(data)