Plotting line with different colors

Question

import pandas as pd
import matplotlib.pyplot as plt
import numpy as np

df1 = pd.DataFrame(np.random.randint(0,15,size=(15, 1)))
df2 = pd.DataFrame(np.random.randint(20,35,size=(10, 1)))


frames = [df1, df2]
result = pd.DataFrame(pd.concat(frames))

df3 = result.cumsum()
df3 = df3.reset_index(drop=False)
print(df3)
df3.plot(y=0)
plt.show()

Is it possible to plot the df3 line with two different colors? First color to be for rows 0 to 14 and second color for rows 15 to 24. In a way I want to mark where df1 has ended and df2 has started.

Answer 1

What about

#[...]
df3 = result.cumsum()
df3 = df3.reset_index(drop=False)
plt.plot(df3.mask(df3.apply(lambda x: x.index < 15))[0], color='blue')
plt.plot(df3.mask(df3.apply(lambda x: x.index > 15))[0], color='green')
plt.show()
plt.close()# do not forget this to save you from Runtime Error.