TypeError: 'range' object does not support item assignment处理方法

vectorsum.py
#!/usr/bin/env/python
import sys
from datetime import datetime
import numpy as np

# def numpysum(n):
#     a = np.arange(n) ** 2
#     b = np.arange(n) ** 3
#     c = a + b
#     return c

def pythonsum(n):
    a = range(n)
    b = range(n)
    c = []
    for i in range(len(a)):
        a[i] = i ** 2
        b[i] = i ** 3
        c.append(a[i] + b[i])
    return c

size = int(sys.argv[1])
print (size)

start = datetime.now()
c = pythonsum(size)
delta = datetime.now() - start
print ("The last 2 elements of the sum", c[-2:])
print ("PythonSum elapsed time in microseconds", delta.microseconds)
# start = datetime.now()
# c = numpysum(size)
# delta = datetime.now() - start
# print ("The last 2 elements of the sum", c[-2:])
# print ("NumPySum elapsed time in microseconds", delta.microseconds)
----------------------------------------------------------------------------
运行结果：

D:>python vectorsum.py 1000
1000
Traceback (most recent call last):
File "vectorsum.py", line 26, in <module>
c = pythonsum(size)
File "vectorsum.py", line 17, in pythonsum
a[i] = i ** 2
TypeError: 'range' object does not support item assignment

----------------------------------------------------------------------------------------

将pythonsum函数修改如下： 

def pythonsum(n):
    a = list(range(n))
    b = list(range(n))
    c = []
    for i in range(len(a)):
        a[i] = i ** 2
        b[i] = i ** 3
        c.append(a[i] + b[i])
    return c



运行正常，通过
-----------------------------------------------------------