[Pig-user] Merging multiple columns into 2 columns

I have data in an HBase table in stored in the following format:

rowkey group_id:1 group_id:2 ... group_id:n
2fcab50712467eab4004583eb8fb7f89 1 0 1
085125e8f7cdc99fd91dbd7280373c5b 0 1 0
dd53e23487da03fd02396306d248cda0 2 1 0

where the column family group_id contains one column for each set of data
and the number is the number of times that the hash is present in the set of
data.

I need to reformat the data and obtain the output in the following format:

hash group_id
2fcab50712467eab4004583eb8fb7f89 1
dd53e23487da03fd02396306d248cda0 1
dd53e23487da03fd02396306d248cda0 1
085125e8f7cdc99fd91dbd7280373c5b 2
dd53e23487da03fd02396306d248cda0 2
...
2fcab50712467eab4004583eb8fb7f89 n

Any ideas on how to achieve this? I'm really at a loss here.