Source code for c3.optimizers.optimizer

"""Optimizer object, where the optimal control is done."""

import os
import time
from typing import Callable, Union, List, Dict, Optional, Any
import numpy as np
import tensorflow as tf
import hjson
import c3.libraries.algorithms as algorithms
from c3.c3objs import hjson_encode
from c3.experiment import Experiment
from c3.parametermap import ParameterMap
import copy
from tensorboard.plugins.hparams import api as hp
import warnings

[docs]class Optimizer: """ General optimizer class from which specific classes are inherited. Parameters ---------- algorithm : callable From the algorithm library store_unitaries : boolean Store propagators as text and pickle logger: List Logging classes """ def __init__( self, pmap: ParameterMap, initial_point: str = "", algorithm: Callable = None, store_unitaries: bool = False, logger: List = None, ): self.pmap = pmap self.optim_status: Dict[str, Any] = dict() self.gradients: Dict[str, np.ndarray] = {} self.current_best_goal = 9876543210.123456789 self.current_best_params = None self.evaluation = 0 self.store_unitaries = store_unitaries self.created_by = None self.logname: str = "" self.options = None self.__dir_path: str = "" self.logdir: str = "" self.set_algorithm(algorithm) if not initial_point == "": self.load_best(initial_point) self.logger = [] if logger is not None: self.logger = logger
[docs] def set_algorithm(self, algorithm: Optional[Callable]) -> None: if algorithm: self.algorithm = algorithm else: print("C3:WARNING:No algorithm passed. Using default LBFGS") self.algorithm = algorithms.lbfgs
[docs] def replace_logdir(self, new_logdir): """ Specify a new filepath to store the log. Parameters ---------- new_logdir """ new_logdir = new_logdir.replace(":", "_") old_logdir = self.logdir self.logdir = new_logdir if old_logdir is None: return try: os.remove(os.path.join(self.__dir_path, "recent")) except FileNotFoundError: pass try: os.rmdir(old_logdir) except OSError: pass for logger in self.logger: logger.set_logdir
[docs] def set_exp(self, exp: Experiment) -> None: self.exp = exp
[docs] def set_created_by(self, config) -> None: """ Store the config file location used to created this optimizer. """ self.created_by = config
[docs] def load_best(self, init_point) -> None: """ Load a previous parameter point to start the optimization from. Legacy wrapper. Method moved to Parametermap. Parameters ---------- init_point : str File location of the initial point """ self.pmap.load_values(init_point)
[docs] def start_log(self) -> None: """ Initialize the log with current time. """ self.start_time = time.time() start_time_str = str(f"{time.asctime(time.localtime())}\n\n") with open(self.logdir + self.logname, "a") as logfile: logfile.write("Starting optimization at ") logfile.write(start_time_str) logfile.write("Optimization parameters:\n") logfile.write(hjson.dumpsJSON(self.pmap.opt_map, default=hjson_encode)) logfile.write("\n") logfile.write("Units:\n") logfile.write( hjson.dumpsJSON(self.pmap.get_opt_units(), default=hjson_encode) ) logfile.write("\n") logfile.write("Algorithm options:\n") logfile.write(hjson.dumpsJSON(self.options, default=hjson_encode)) logfile.write("\n") logfile.flush() for logger in self.logger: logger.start_log(self, self.logdir)
[docs] def end_log(self) -> None: """ Finish the log by recording current time and total runtime. """ self.end_time = time.time() with open(self.logdir + self.logname, "a") as logfile: logfile.write(f"Finished at {time.asctime(time.localtime())}\n") logfile.write(f"Total runtime: {self.end_time - self.start_time}\n\n") logfile.flush() for logger in self.logger: logger.end_log(self, self.logdir)
[docs] def log_best_unitary(self) -> None: """ Save the best unitary in the log. """ with open(self.logdir + "best_point_" + self.logname, "w") as best_point: propagators = self.exp.propagators for gate, U in propagators.items(): best_point.write("\n") best_point.write(f"Re {gate}: \n") best_point.write(f"{np.round(np.real(U), 3)}\n") best_point.write("\n") best_point.write(f"Im {gate}: \n") best_point.write(f"{np.round(np.imag(U), 3)}\n")
[docs] def log_parameters(self, params) -> None: """ Log the current status. Write parameters to log. Update the current best parameters. Call plotting functions as set up. """ if self.optim_status["goal"] < self.current_best_goal: self.current_best_goal = self.optim_status["goal"] self.current_best_params = self.optim_status["params"] self.pmap.store_values( path=self.logdir + "best_point_" + self.logname, optim_status=self.optim_status, ) if self.store_unitaries: self.exp.store_Udict(self.optim_status["goal"]) self.exp.store_unitaries_counter += 1 with open(self.logdir + self.logname, "a") as logfile: logfile.write( f"\nFinished evaluation {self.evaluation} at {time.asctime()}\n" ) # logfile.write(hjson.dumpsJSON(self.optim_status, indent=2)) logfile.write(hjson.dumpsJSON(self.optim_status, default=hjson_encode)) logfile.write("\n") logfile.flush() for logger in self.logger: logger.log_parameters(self.evaluation, self.optim_status)
[docs] def goal_run( self, current_params: Union[np.ndarray, tf.constant] ) -> Union[np.ndarray, tf.constant]: """ Placeholder for the goal function. To be implemented by inherited classes. """ raise NotImplementedError("Implement this function in a subclass")
[docs] def goal_run_with_grad(self, current_params): with tf.GradientTape(watch_accessed_variables=False) as t: goal = self.goal_run(current_params) grad = t.gradient(goal, current_params) return goal, grad
[docs] def lookup_gradient(self, x): """ Return the stored gradient for a given parameter set. Parameters ---------- x : np.array Parameter set. Returns ------- np.array Value of the gradient. """ key = str(x) gradient = self.gradients.pop(key) if np.any(np.isnan(gradient)) or np.any(np.isinf(gradient)): # TODO: is simply a warning sufficient? gradient[ np.isnan(gradient) ] = 1e-10 # Most probably at boundary of Quantity gradient[ np.isinf(gradient) ] = 1e-10 # Most probably at boundary of Quantity return gradient
[docs] def fct_to_min( self, input_parameters: Union[np.ndarray, tf.constant] ) -> Union[np.ndarray, tf.constant]: """ Wrapper for the goal function. Parameters ---------- input_parameters : [np.array, tf.constant] Vector of parameters in the optimizer friendly way. Returns ------- [np.ndarray, tf.constant] Value of the goal function. Float if input is np.array else tf.constant """ pars = [] # We use zip to create pairs of Quantity objects and their new bare numeric parameter values. # Then we compute the new physical value and store it in the status. for par, y in zip(self.pmap.get_parameters(), np.array(input_parameters)): pars.append(par.get_other_value(y).tolist()) self.optim_status["params"] = pars if isinstance(input_parameters, np.ndarray): current_params = tf.constant(input_parameters) goal = self.goal_run(current_params) self.optim_status["goal"] = float(goal) goal = float(goal) else: current_params = input_parameters goal = self.goal_run(current_params) self.optim_status["goal"] = float(goal) self.log_parameters(input_parameters) return goal
[docs] def fct_to_min_autograd(self, x): """ Wrapper for the goal function, including evaluation and storage of the gradient. Parameters ---------- x : np.array Vector of parameters in the optimizer friendly way. Returns ------- float Value of the goal function. """ current_params = tf.constant(x) goal, grad = self.goal_run_with_grad(current_params) if isinstance(grad, tf.Tensor): grad = grad.numpy() gradients = grad.flatten() for i in tf.where(gradients == 0).numpy().tolist(): warnings.warn( f"{self.pmap.get_key_from_scaled_index(i[0])} has no gradient. This might indicate no usage for current experiment.", Warning, ) self.gradients[str(current_params.numpy())] = gradients # We use zip to create pairs of Quantity objects and their new bare numeric parameter values. # Then we compute the new physical value and store it in the status. self.pmap.set_parameters_scaled(x) self.optim_status["params"] = [ par.numpy().tolist() for par in self.pmap.get_parameters() ] self.optim_status["gradient"] = gradients.tolist() last_goal = float(goal) self.optim_status["goal"] = last_goal self.log_parameters(current_params) return goal
[docs]class BaseLogger: def __init__(self): pass
[docs] def start_log(self, opt, logdir): self.logdir = logdir
[docs] def log_parameters(self, evaluation, optim_status): pass
[docs] def end_log(self, opt, logdir): pass
[docs]class BestPointLogger(BaseLogger): pass
[docs]class TensorBoardLogger(BaseLogger): def __init__(self): super().__init__() self.opt_map = [] self.writer: None self.store_better_iterations_only = True self.best_iteration = np.inf
[docs] def write_params(self, params, step=0): if not len(self.opt_map) == len(params): raise Exception( f"C3:Error: Different number of elements in opt_map and params. {len(self.opt_map)} vs {len(params)}" ) for i in range(len(self.opt_map)): for key in self.opt_map[i]: if type(params[i]) is float or np.float64: tf.summary.scalar(key, float(params[i]), step=step) elif len(params[i]) == 1: tf.summary.scalar(key, float(params[i][0]), step=step) else: for jj in range(len(params[i])): tf.summary.scalar( key + "_" + str(jj), float(params[i][jj]), step=step )
[docs] def set_logdir(self, logdir): print("new Tensorboard Logdir") self.logdir = logdir
[docs] def start_log(self, opt, logdir): self.opt_map = opt.pmap.get_opt_map() print("create log at", logdir) self.writer = tf.summary.create_file_writer( logdir=logdir, ) with self.writer.as_default(): self.write_params(opt.pmap.get_parameters()) tf.summary.text( "Parameters", hjson.dumpsJSON( opt.pmap.asdict(instructions_only=False), indent=2, default=hjson_encode, ), step=0, ) self.writer.flush() hparams = dict() for k, hpar in opt.pmap.get_not_opt_params().items(): val = hpar.numpy() if len(val.shape) < 1 or val.shape[0] < 2: hparams[k] = float(hpar) else: for i, v in enumerate(val.tolist()): hparams[f"{k}_{i}"] = v with self.writer.as_default(): hp.hparams(hparams) self.writer.flush()
[docs] def log_parameters(self, evaluation, optim_status): if self.store_better_iterations_only: if optim_status["goal"] > self.best_iteration: return else: self.best_iteration = optim_status["goal"] opt_status = copy.deepcopy(optim_status) with self.writer.as_default(): self.write_params(opt_status.pop("params"), evaluation) tf.summary.scalar("goal", opt_status.pop("goal"), step=evaluation) if "gradient" in opt_status: tf.summary.histogram( "gradient", tf.clip_by_value(opt_status.pop("gradient"), -3, 3), step=evaluation, ) opt_status.pop("time") for k, v in opt_status.items(): if type(v) is float: tf.summary.scalar(k, v, step=evaluation) elif type(v) is list: tf.summary.histogram(k, v, step=evaluation) else: # print(k, v) raise Warning( f"Elements of type {type(v)}, here {k}, are not yet implemented to be logged " ) self.writer.flush()