def permutation_importances(rf, X_train, y_train, metric):
    baseline = metric(rf, X_train, y_train)
    imp = []
    for col in X_train.columns:
        save = X_train[col].copy()
        X_train[col] = np.random.permutation(X_train[col])
        m = metric(rf, X_train, y_train)
        X_train[col] = save
        imp.append(baseline - m)
    return np.array(imp)