def plot_wikipedia_cost(model, model_df, cost_func, save_pdf=False):
output = '/tmp/wikipedia_cost.pdf' if save_pdf else None
df = _select_df(model_df, 'application', 'wikipedia')
target = _train(model, df)
plotter = Plotter(xlim=(0, 3.5))
plotter.update_config(s=40)
plotter.plot_cost_model(model, target, cost_func, output)
print('Prediction of the Wikipedia application cost.')
