Matplotlib и Numpy предназначены для go рука об руку, а арифметика c в массивах НАМНОГО проще, чем в списках, поэтому забудьте о преобразовании в списки
data = np.array([ # shape of data is (6, 2) - six rows, two columns
[0, 2],
[0, 3],
[0, 6],
[0, 7],
[7, 9],
[7, 8],
])
x, y = data.T # x, y are two Numpy arrays, their shape (6,) because data.T is (2, 6)
# create a figure with two sublots in a single row, "1,2"
# stretch the h-size to accomodate two subplots,
# use exactly the same x limits and ticks on both subplots
fig, (ax0, ax1) = plt.subplots(1,2, figsize=(8,3), sharex=True)
# in one subplot the original data, in the other the modified x
ax0.plot(x, y)
ax1.plot(x+1, y) # simply add 1 to the array x