Read from file into dictionary

[growthndevlpmnt]

if this was my input file:

AATGC
AGGC
0.0
0.0
4
ATGC
4
ATGC
1 1 A A 1
1 2 A T 0
1 3 A G 0
1 4 A C 0
2 1 T A 0
2 2 T T 1
2 3 T G 0
2 4 T C 0
3 1 G A 0
3 2 G T 0
3 3 G G 1
3 4 G C 0
4 1 C A 0
4 2 C T 0
4 3 C G 0
4 4 C C 1

How could I generate a dictionary using the last 16 lines? I would like to combine the two letters and use them as a key, and then us the last int as the value stored at the key.

This is supposed to be a scoring matrix. If there is a better way to do this, by all means please help me be more efficient.

there will be files that have ints longer than one digit. So i tried to dump the contents into a list and iterate/take slices, but it did not work.

Please help!

[andrean]

result = dict()

with open('filename.txt', 'r') as source_file:
    for line in source_file.readlines():
        parts = line.split()
        if len(parts) < 5: continue
        key = '{0}{1}'.format(parts[2], parts[3])
        result[key] = parts[4]

print result