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perl "vlookup" using a hash?

Hi,

I have a text file with two columns like follows

9781 Person1
978 Person2
9782 Person3

I then have an ID that I want to look up from this file - returning the 2nd column for the first match it finds.

For example, if my ID = “978”, I want it to return “Person2” as I want it to be an exact match against columnA.

ID “9782” would then return “Person3”

Can this be done with a hash and using exist?

(This probably sounds so basic that it reads like a homework question, it’s really not!)

wilcoxon

Yes. As a one-liner, this would do it. It can be easily expanded into a script (or portion thereof).

perl -ne '($id,$per) = split; $data{$id} = $per; END { print $data{978}, "\n" if exists($data{978}) }'

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yelbow

ASKER

Thanks! I've realised I need to complicate this further - it seems that ColumnA doesn't always contain a unique value. For example, the data could be:

9781 Person1
978 Person2
978 Person4
9782 Person3

I think a has requires a unique match on the key (?) and if not returns the last one it finds (?) (at least it seems that way!)

is there a way to return the first match it finds on $id?

(Apologies for extending the question!)

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wilcoxon

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yelbow

ASKER

Thanks!

perl &quot;vlookup&quot; using a hash?

perl "vlookup" using a hash?