It largely depends on what you want to do with the data...are you trying to construct a summary of the digits based on the city keys? In that case I would create a hash of arrayrefs and then manipulate the data as you need: 
while(<DATA>){
 ($city,$num)=split;
 push( @{$myhash{$city}}, $num );
}

[download]
Now you have a hash with the city names as keys and each corresponding digit included in an arrayref of values. This node has some good insight into working with these data structures.

In reply to Re: arrays or hashes by insensate
in thread arrays or hashes by Anonymous Monk

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