Adding two plots with differnts x start

I’m trying to merge two curves into only one, but the originals two lines are shifted horizontally:

import numpy as np

a = np.array([[1,2,3], # x value
               [0.3, 0.5, 0.6]]) # y value
b = np.array([[2,3,4], [0.5,0.4,0.3]])

I need c = [[1,2,3,4],[0.3, 1, 1, 0.3]]

How can I done?

>Solution :

You can use pandas:

import pandas as pd
import numpy as np

a = np.array([[1,2,3], # x value
           [0.3, 0.5, 0.6]]) # y value
b = np.array([[2,3,4], [0.5,0.4,0.3]])

pd.concat(map(pd.DataFrame,[a.T, b.T])).groupby(0).sum().plot()

Output: