I have a set of split data-lines read in from <$IN> in this generalised format:

ID   Type Pos
1    1    10
2    1    11
3    1    11
4    1    15
5    2    5
6    2    5
7    2    7

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These can either be pushed into an array or used to create hash keys (i'm not sure which one suits the task at hand more). My aim is to identify lines that are duplicates based only on Type + Pos, for example from the above data set: 

2    1    11
3    1    11
5    2    5
6    2    5

[download]

Are duplicates. Once a duplicate is identified, the unique IDs of the two offending lines are stored for use later on in the script. Normally I would simply use an incrementing hash to detect duplicate entries, looking for any values >1 - but now that I have the ID column to handle as well, i'm not sure how to do this. Could anybody share any code or tips on how to accomplish this? Thanks!

In reply to Identifying duplicates in array or hash based on a subset of data by Anonymous Monk

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