optuna.visualization.plot_slice(study, params=None, *, target=None, target_name='Objective Value')[source]

Plot the parameter relationship as slice plot in a study.

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


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

import optuna

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=10)

fig = optuna.visualization.plot_slice(study, params=["x", "y"])
  • study (Study) – A Study object whose trials are plotted for their target values.

  • params (Optional[List[str]]) – Parameter list to visualize. The default is all parameters.

  • target (Optional[Callable[[FrozenTrial], float]]) –

    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.


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

  • target_name (str) – Target’s name to display on the axis label.


A plotly.graph_objs.Figure object.

Return type