Percentile Pruner

import optuna
from optuna.pruners import PercentilePruner


def objective(trial):
    s = 0
    for step in range(20):
       x = trial.suggest_float(f"x_{step}", -5, 5)
       s += x**2
       trial.report(s, step)
       if trial.should_prune():
            raise optuna.TrialPruned()
    return s


pruner = PercentilePruner(25.0)
study = optuna.create_study(pruner=pruner)
study.optimize(objective, n_trials=20)