from typing import Callable
from typing import Optional
from optuna._experimental import experimental
from optuna.logging import get_logger
from optuna.study import Study
from optuna.study import StudyDirection
from optuna.trial import FrozenTrial
from optuna.trial import TrialState
from optuna.visualization.matplotlib._matplotlib_imports import _imports
if _imports.is_successful():
from optuna.visualization.matplotlib._matplotlib_imports import Axes
from optuna.visualization.matplotlib._matplotlib_imports import plt
_logger = get_logger(__name__)
[docs]@experimental("2.2.0")
def plot_optimization_history(
study: Study,
*,
target: Optional[Callable[[FrozenTrial], float]] = None,
target_name: str = "Objective Value",
) -> "Axes":
"""Plot optimization history of all trials in a study with Matplotlib.
.. seealso::
Please refer to :func:`optuna.visualization.plot_optimization_history` for an example.
Example:
The following code snippet shows how to plot optimization history.
.. plot::
import optuna
def objective(trial):
x = trial.suggest_uniform("x", -100, 100)
y = trial.suggest_categorical("y", [-1, 0, 1])
return x ** 2 + y
sampler = optuna.samplers.TPESampler(seed=10)
study = optuna.create_study(sampler=sampler)
study.optimize(objective, n_trials=10)
optuna.visualization.matplotlib.plot_optimization_history(study)
Args:
study:
A :class:`~optuna.study.Study` object whose trials are plotted for their target values.
target:
A function to specify the value to display. If it is :obj:`None`, the objective values
are plotted.
target_name:
Target's name to display on the axis label and the legend.
Returns:
A :class:`matplotlib.axes.Axes` object.
"""
_imports.check()
return _get_optimization_history_plot(study, target, target_name)
def _get_optimization_history_plot(
study: Study,
target: Optional[Callable[[FrozenTrial], float]],
target_name: str,
) -> "Axes":
# Set up the graph style.
plt.style.use("ggplot") # Use ggplot style sheet for similar outputs to plotly.
_, ax = plt.subplots()
ax.set_title("Optimization History Plot")
ax.set_xlabel("#Trials")
ax.set_ylabel(target_name)
cmap = plt.get_cmap("tab10") # Use tab10 colormap for similar outputs to plotly.
# Prepare data for plotting.
trials = [t for t in study.trials if t.state == TrialState.COMPLETE]
if len(trials) == 0:
_logger.warning("Study instance does not contain trials.")
return ax
best_values = [float("inf")] if study.direction == StudyDirection.MINIMIZE else [-float("inf")]
comp = min if study.direction == StudyDirection.MINIMIZE else max
for trial in trials:
trial_value = trial.value
assert trial_value is not None # For mypy
best_values.append(comp(best_values[-1], trial_value))
best_values.pop(0)
# Draw a scatter plot and a line plot.
if target is None:
ax.scatter(
x=[t.number for t in trials],
y=[t.value for t in trials],
color=cmap(0),
alpha=1,
label=target_name,
)
ax.plot(
[t.number for t in trials],
best_values,
marker="o",
color=cmap(3),
alpha=0.5,
label="Best Value",
)
else:
ax.scatter(
x=[t.number for t in trials],
y=[target(t) for t in trials],
color=cmap(0),
alpha=1,
label=target_name,
)
ax.legend()
return ax