changing sequence to array

[amitsoni.1984 at gmail.com]

Hi,
I am using the code given below where A is a matrix and row is a
sequence. But it gives following error:

-------- error------
    A[a,:]=row
ValueError: setting an array element with a sequence.

--------------code----------------
#!/usr/bin/python
import numpy
file1 = open('matrix.txt', 'r')

count =  0
a=0
b=0
c=0
d=0
e=0
A = numpy.zeros([4,4])
B= numpy.zeros([4,4])
C = numpy.zeros([4,4])
D = numpy.zeros([4,4])
E = numpy.zeros([4,4])
while 1:
    lineStr = file1.readline()
    if not(lineStr):
        break

    count = count + 1
    row=lineStr.split()
    if count<=4:
        A[a,:]=row
        a=a+1
    elif count<=8:
        B[b,:]=row
        b=b+1
    elif count<=12:
        C[c,:]=row
        c=c+1
    elif count<=16:
        D[d,:]=row
        d=d+1
    elif count<=20:
        E[e,:]=row
        e=e+1

file1.close()
---------end of code-------------

is there any way to change a sequence to array so that the above
operation could be executed?
thank you
Amit