# Finding the min and max
c_max_index = argrelextrema(df.flow.values, np.greater, order=3)
c_min_index = argrelextrema(df.flow.values, np.less, order=3)

df['min_extreme'] = df.flow[c_min_index[0]]
df['max_extreme'] = df.flow[c_max_index[0]]

# Plotting the values for the graph above
plt.plot(df.flow.values)
upper_bound = plt.plot(c_max_index[0], df.flow.values[c_max_index[0]], linewidth=0.8, c='g')
lower_bound = plt.plot(c_min_index[0], df.flow.values[c_min_index[0]], linewidth=0.8, c='r')