plot_contour

optuna.visualization.plot_contour(study, params=None, *, target=None, target_name='Objective Value')

Plot the parameter relationship as contour plot in a study.

Note that, if a parameter contains missing values, a trial with missing values is not plotted.

Parameters:

• study (Study) – A Study object whose trials are plotted for their target values.

• params (list[str] | None) – Parameter list to visualize. The default is all parameters.

• target (Callable[[FrozenTrial], float] | None) –

  A function to specify the value to display. If it is None and study is being used for single-objective optimization, the objective values are plotted.

  Note

  Specify this argument if study is being used for multi-objective optimization.

• target_name (str) – Target’s name to display on the color bar.

Returns:

A plotly.graph_objects.Figure object.

Return type:

Figure

Note

The colormap is reversed when the target argument isn’t None or direction of Study is minimize.

The following code snippet shows how to plot the parameter relationship as contour plot.

import optuna
from plotly.io import show


def objective(trial):
    x = trial.suggest_float("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=30)

fig = optuna.visualization.plot_contour(study, params=["x", "y"])
show(fig)