How to replace values?

Hello all,

I have a list of genes as follows (A)

Number? GeneName
0???????????? YAR003W
1???????????? YAR007C
2???????????? YAR008W
3???????????? YBL035C
4???????????? YBL111C
5???????????? YBL112C

And I have a list of gene interactions as follows (B)

0 -> 1
1 -> 5
3 -> 4
2 -> 3

I want to replace the values in (B) with the corresponding values in
(A) ie, I want to achieve the following

0 -> 1 replaced with YAR003W ->YAR007C
1 -> 5 replaced with YAR007C -> YBL112C
3 -> 4 replaced with YBL035C ->?? YBL111C
2 -> 3 replaced with YAR008W -> YBL035C

The example is simple with (A) and (B) only having a few lines.? But
in reality, (A) may contain more than 1000 genes and (B) may contain
thousands of interactions.

Any suggestions? on how to achieve the above task are welcomed!



--
Suhaila Zainudin
PhD Candidate
Universiti Teknologi Malaysia