Suppose I have the following input: 
STORE     PRODUCT_ID
====================
Sydney    12
Sydney    14
Canberra  12
Canberra  18

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To create a hash that will allow me to determine if a store has a product I can use: 
my %hash;
$hash{(split)[0]}{(split)[1]} = 1 foreach <>;

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How can I achieve a similar result using map?

In reply to Possible for Map to create Hash of Hash? by konnjuta

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