calculate the mid points of a vector using Python

I started to learn python from scratch. I got some issues while doing the following problem.

I have the following vector ,x_vector = (0,1,2,3,4,5,6,7,8,9). Using this vector, I need to create this new vector x1 = (-0.5,0.5,1.5,2.5,3.5,4.5,5.5,6.5,7.5,8.5,9.5).

Basically the desired vector should have first element -0.5, mid points between each elements and the last element +0.5.

The code I tried so far as follows:

import numpy as np
x_vector=np.array([0,1,2,3,4,5,6,7,8,9])
x=len(x_vector)
mid=np.zeros(x+1)

for i in range (0,x):
    if i==0 :
        mid[i]= x_vector[i]-0.5
    else :
        mid[i]=(x_vector[i] + x_vector[i+1])/2
        i +=1

Seems like this doesn't give the desired output. Can you one help me to figure out what can I do to get correct output?