Linearly interpolate data in python

import numpy as np

a      = np.array([1.2, 2.7, 0.3]) # data to linearly interpolate
b      = []                                  # Data storage location after linear interpolation
divnum = 4                               # Division number

for n in np.arange(a.shape[0]-1):
    for i in np.arange(divnum):
        c= round(a[n] + (a[n+1]-a[n])/divnum * i,2)  # Linear interpolation processing
        b.append(c)              # Store data
b.append(a[a.shape[0]-1]) # store last data

np.savetxt('test.txt', b,fmt="%.2f") # save to text